Door mounted oven controls

A microwave oven having the control panel mounted on the door. The control panel includes a plurality of pushbutton switches for the user to push to control the speed, time, etc. for variable cooking in the microwave oven. The switches communicate to an electronic controller also mounted on the door. The controller converts user input into signals that control the various operating components of the oven, such as the magnetron. The controller is connected with these components via a flexible printed circuit cable which bridges the space between the door and the oven near or through the hinge area of the oven.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to improvements in microwave ovens 
and more particularly to improvements in mounting the microwave oven 
control panel. 
2. Brief Description of the Prior Art 
Microwave ovens, indeed all ovens, have heretofore been constructed with a 
separate area mounted on the oven housing especially dedicated for the 
mounting thereon of the microwave oven controls. This separate area has 
been commonly known as a control panel. A good example of the state of the 
prior art can be seen by reference to U.S. Pat. to Ronald G. Buck, No. 
4,162,381, assigned to the assignee of the present invention. 
This location was dictated because the components to be controlled were 
located inside the main oven housing. The only other conceivable location 
of the control panel, the door, was not an obvious location primarily 
because of two factors: first, there was the difficulty of communicating 
signals from the controls mounted on the rotably mounted door to the 
components mounted in the fixed oven housing; and second, there was the 
difficulty in communicating these signals across the space between the 
door and the oven housing which, in a microwave oven, was subject to high 
electromagnetic interference (noise) from leakage from the cavity, 
magnetron and other high power electrical devices mounted with the oven 
housing. 
SUMMARY OF THE INVENTION 
The present invention overcomes the first difficulty by communicating 
signals between the door mounted control panel and the oven housing 
mounted components by means of a flexible cable: printed circuit, fiber 
optics or an equivalent; mounted such that it runs through apertures in 
the door and oven housing substantially about the axis of rotation of the 
axially mounted door. 
The present invention overcomes the second difficulty by mounting in the 
door an electronic controller which receives highly sensitive low power 
signals from the control panel switches and converts them into relatively 
higher power signals to be communicated to the oven's operating components 
which, due to their higher power levels, are relatively insensitive to the 
electromagnetic noise present in and about the space between the door and 
the oven housing member. 
These and other advantages and objects of the present invention will be 
more readily appreciated in the following detailed description when taken 
in view of the accompanying drawings, in which like reference numerals 
refer to like elements throughout the figures.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
A microwave oven (shown generally as 1) is conventionally constructed with 
a housing member 10 and a door 4. Mounted interior to such a housing 
member 10 are the various operating components of the microwave oven 1 
such as the cooking cavity, the magnetron (not shown), which emits 
microwaves, the power supply (not shown), and various sensors and other 
circuits and devices (also not shown). These components have been 
conventionally controlled, either manually or elecrically, by manually 
operable controls mounted on the housing member 1. Such an arrangement is 
shown in FIG. 1 of U.S. Pat. No. 4,162,381, to Buck. The housing area in 
which these controls have been heretofore mounted is known as a control 
panel. As can be seen by reference to Buck '381, this control panel 
requires an area on the housing member facing the user thus reducing the 
percentage of area on the front of the microwave oven usable as a cooking 
cavity. Should the control panel instead be mounted on the door, as in 
FIG. 1 of the present application, the frontal area consumed by the 
cooking cavity 12 could be enlarged to cover substantially the entire 
frontal area of the microwave oven 1; or similarly, the frontal area of 
the microwave oven 1 can be reduced. In addition to reducing wasted space, 
mounting the control panel on the oven door has the advantage of 
delivering a higher capacity oven per square inch of oven front, which is 
highly important to the consumer. He gets either a smaller sized oven with 
the same capacity as before or a larger capacity oven no larger in size. 
Additionally, by mounting the control panel 3 on the door 4 rather than on 
the housing member 10, heavy oven components, such as a power supply 
transformer conventionally mounted on the side of the housing member as in 
FIG. 4 of Buck '381, can now be mounted to the rear, thus increasing the 
amount of rearward weight relative to the front to assist in preventing 
forward tipping of the microwave oven 1 when the door is open. 
In the preferred embodiment, the control panel 3 is mounted on the upper 
right hand portion of the microwave oven door 4. The control panel is 
composed of a plurality of pushbutton switches 6 of conventional design. 
Those switches 6 may also conveniently be of the capacitive touch type. 
The location of the control panel 3 on the door 4 is not critical. The 
present location was chosen to allow the inclusion in the door 4 of a 
semitransparent window 5 which allows the user convenient visual access to 
the oven's cooking cavity 12 during oven operation. 
The switches 6 are electrically connected to an electronic controller 14 
mounted in the door 4 just interior to the control panel 3. This 
controller 14 receives input from the switches 6 and converts them into 
signals to be communicated to the oven's operating components. The 
location of the controller 14 near the switches 6 on the door 4 is 
necessary due to the presence of electromagnetic noise emitting from the 
cooking cavity 12 and the magnetron through the space between the door 3 
and the oven housing member 10. The signals from the switches 6 to the 
controller 14 are of lower power and voltage and would thus tend to be 
more sensitive to this noise if they were to pass through the high noise 
region. However, the output from the controller 14 to the oven's 
components can be adjusted such that the noise level will cause no 
noticeable effect upon signal transmission. 
The output signals from the controller 14 to the oven's components and the 
electric power and feedback signals to the controller 14 and switches 6 
are transmitted, in the preferred embodiment, via a flexible printed 
circuit cable 16, such as that available from Sheldahl, Inc., Electrical 
Products Division, Northfield, MN. The cable 16 is connected at one end to 
the controller 14, as in FIG. 2. It then runs out an aperture 30 near the 
hinge area 18 of the door 4, across the space between the door 4 and 
housing member 10, as in FIGS. 2 and 3, into a second aperture 32 mounted 
in the housing member 10 near the hinge area 18, and from there to the 
oven's operating components. In the preferred embodiment, these apertures 
30 and 32 are located at or slightly interior to the axis of rotation of 
the door 4. Thus, in a typical hinge arrangement 40 of FIG. 3, the pivot 
42 is located just above the apertures 30 and 32. While if the hinge 44 is 
arranged axially as in FIG. 2, that is, the hinge 44 is a coupling running 
vertically along the axis of rotation, the apertures 30 and 32 would be 
located just to the interior of the axis rotation. This arrangement of 
apertures 30 and 32 vis-a-vis hinges 40 and 44 allows the flexible cable 
16 to flex minimally during the opening and closing of the door 4. It may 
also be appreciated that the present invention may be practised by 
locating the apertures 30 and 32 exterior to the axis of rotation. 
However, this is not aesthetically desirable because it increases the 
visibility of the unsightly cable 16, and causes additional flexing of the 
cable 16 during the opening and closing of the door 4. Flexure should be 
minimized because, as in all mechanical devices, flexure or bending causes 
fatigue, which could lead, over time, to the breakdown or the printed 
circuit cable 16. To allow space for the flexure to take place, cavities 
20 and 22 are provided. 
Disposed within the cable 16 are printed conductors 24, the number of which 
depend upon the designer's choice. At a minimum there should be three, 
which correspond to a power input to the controller 14 and switches 6, a 
signal input and a signal output. The component from which or to which a 
signal is sent may conventionally be identified by an address prefix or by 
a multiplexing arrangement. However, it is equally possible to have as 
many conductors 24 as there are devices to be controlled. 
As the conductors 24 are printed, they lie extremely flat and are ordered 
within the cable 16 into a plane such they they pose little resistance to 
bending in a direction normal to the plane. Thus there is a minimal 
interference to the opening and closing of the door 4 as well as minimal 
fatigue. 
An alternative embodiment of the present invention may use a fiber optics 
cable 50 to transmit signals to and from the controller 14. Fiber optics 
cables are well adapted to be used in the present invention because they 
are composed of a plastic material and are, therefore, flexible. 
The fiber optics cable 50 is mounted in the same manner as the flexible 
printed circuit cable 16. Mounted in the door 4, the cable runs out an 
aperture 54 in the door 4 located at or slightly interior to the axis of 
rotation of the hinge 52. From there, the fiber optics cable 50 crosses 
the space between the door 4 and housing member 10 to enter a second 
aperture 56 mounted in the housing member 10. As in FIG. 2, cavities 20 
and 22 are located in the door 4 and housing member 10 to allow the fiber 
optics cable 50 room to flex. 
This completes a description of the preferred embodiment and one 
alternative thereto. Various modifications may be made to the 
specifications above-enumerated without departing from the scope of the 
present invention, in which