Patent Grant
10292212
This invention relates generally to the field of microwave ovens.
The modern microwave oven, for all it's apparent sophistication, has stagnated in technological progress over the past decade. The need for improvement is no more necessary than in cooking thoroughness, uniformity, and in oven capacity. Current solutions are severely limited. For example, the best solution for uniform cooking that has been developed so far is to rotate a plate supporting the object to be heated in the oven. However, this only captures variability of constructive interference of microwaves in two dimensions. Additionally, microwave oven capacity has technical and practical limitations that need to be overcome before design options can become more robust. Modern home design is moving towards lean and minimalistic features, while still providing all the modern conveniences, including microwave ovens. However, current ovens are not compatible with many new designs because of shape and power requirements, among other reasons. Thus, there is significant room for improvement to current microwave design and functional aspects.
A double-cavity microwave oven is described herein that addresses some of the problems in the art described above. In general, the microwave oven includes two cavities, two corresponding magnetrons and waveguides, and a moveable barrier disposed between the two cavities. The disclosed microwave oven provides several benefits over other microwave ovens. First, this microwave oven provides flexible cavity size to accommodate either personal-sized meals or larger food items. Second, the disclosed microwave oven offers flexible power consumption compared with other microwave ovens. Having two magnetrons, this microwave oven can cook with one magnetron or alternate power between the two magnetrons in cooking two meals simultaneously. For large meals, power is provided to both magnetrons simultaneously. One benefit of this arrangement is that a lower supply power provides higher cooking power and flexibility.
In one embodiment of the claimed invention, a double-cavity microwave oven is disclosed that includes a first and a second cooking cavity, a moveable barrier disposed between the first and the second cavity, a first and a second magnetron, and a first and a second waveguide corresponding to the first and the second magnetron, respectively. The first cavity is electromagnetically isolated from the second cavity, and, as the barrier moves, the size of the first cavity relative to the second cavity changes. As the barrier is in a first position, the first waveguide directs microwaves from the first magnetron to the first cavity and the second waveguide directs microwaves from the second magnetron to the second cavity. As the barrier is in a second position, the first and the second waveguide direct microwaves from the first and the second magnetron to the first cavity. Various other embodiments are also disclosed including additional features.
A more particular description of the invention briefly described above is made below by reference to specific embodiments. Several embodiments are depicted in drawings included with this application, in which:
A detailed description of the claimed invention is provided below by example, with reference to embodiments in the appended figures. Those of skill in the art will recognize that the components of the invention as described by example in the figures below could be arranged and designed in a wide variety of different configurations. Thus, the detailed description of the embodiments in the figures is merely representative of embodiments of the invention, and is not intended to limit the scope of the invention as claimed.
The descriptions of the various embodiments include, in some cases, references to elements described with regard to other embodiments. Such references are provided for convenience to the reader, and to provide efficient description and enablement of each embodiment, and are not intended to limit the elements incorporated from other embodiments to only the features described with regard to the other embodiments. Rather, each embodiment is distinct from each other embodiment. Despite this, the described embodiments do not form an exhaustive list of all potential embodiments of the claimed invention; various combinations of the described embodiments are also envisioned, and are inherent from the descriptions of the embodiments below. Additionally, embodiments not described below that meet the limitations of the claimed invention are also envisioned, as is recognized by those of skill in the art.
Throughout the detailed description, various elements are described as “off-the-shelf” or otherwise commonly known or used in the art. As used herein, descriptions mean “pre-manufactured” and/or “pre-assembled.”
In some instances, features represented by numerical values, such as dimensions, quantities, and other properties that can be represented numerically, are stated as approximations. Unless otherwise stated, an approximate value means “correct to within 50% of the stated value.” Thus, a length of approximately 1 inch should be read “1 inch +/−0.5 inch.” Similarly, other values not presented as approximations have tolerances around the stated values understood by those skilled in the art. For example, a range of 1-10 should be read “1 to 10 with standard tolerances below 1 and above 10 known and/or understood in the art.”
In general, microwave ovens are subject to certain power and dimension limitations in order to function properly. Microwave frequencies range from 300 MHz to 300 GHz, but the most common frequency used in consumer microwave ovens is 2.45 GHz, which has a wavelength of approximately 12.2 cm. In commercial microwave ovens, the most common frequency is 915 MHz, which has a wavelength of 32.8 cm. This limits the size of microwaves to having at least two dimensions having lengths equal to a half-wavelength multiple to allow for resonance. Common power ratings range from 700 W to 1800 W, depending on the space available for a transformer and the power source the microwave oven is plugged in to. For example, counter-top microwave ovens are configured to be powered through a typical 110-V outlet, whereas some built-in and/or commercial microwave ovens are configured to be powered through a typical 220-V outlet.
While every variety of size and/or power is theoretically available by simply varying the frequency or power output, practical limitations, such as the commercial availability of transformers and magnetrons at desired frequencies, limits economical construction of microwave ovens outside of those commonly constructed. It is thus one object of the microwave oven disclosed herein to provide for flexibility within the current economical restraints.
In some embodiments, the microwave oven includes a single door that provides access by a user to the first and the second cooking cavity. Further embodiments of the single door include those wherein the door thermally and/or electromagnetically segregates the first cavity from the second cavity. In other embodiments, the microwave oven includes a first door corresponding to the first cavity, and a second door corresponding to the second cavity. The first door is adjacent to the second door and the first and the second door each form an electromagnetic seal with the barrier. In various further embodiments of the double-door embodiment, the first door is disposed above the second door, and the first and the second door open in the same direction, or the first door opens upwards and the second door opens down; or the first and the second door are side-by-side and open in the same direction, or away from each other such that the first door opens to the left and the second door opens to the right. Additionally, in some dual-door embodiments, the first or the second door locks and becomes non-operable as the barrier is in the second position.
In various embodiments, the barrier incorporates a variety of beneficial features. For example, in some embodiments, the barrier thermally segregates the first cavity from the second cavity. In some embodiments, the barrier is moveable in a first direction, such as to expand one cavity and contract the other, and is fixed in a second direction perpendicular to the first directions such that the barrier is non-removeable from the microwave oven. Some embodiments of the barrier include one or more lights and microwave shielding between the lights and the first magnetron, the second magnetron, or both. The shielding is at least partially transparent to visible light, but at least mostly opaque to microwaves. In some embodiments wherein the barrier includes the lights, the barrier includes a first light facing the first cavity and a second light facing the second cavity. Another feature included in some embodiments is motorization of the barrier such that an electric motor and a transmission move the barrier between the first and the second positions.
One difficulty with heating an object in a microwave oven is achieving uniform heating throughout the object. One benefit of the claimed invention is that more even heating is achieved through three-dimensional motion, either of the object being heated, the cavity, or the microwave source. For example, in some embodiments, at least one of the first or the second cavity oscillates relative to at least one of the first or the second waveguide such that a first path length from the at least one waveguide to a first wall of the at least one cavity and a second path length from the at least one waveguide to a second wall of the at least one cavity varies with the oscillation. This causes the zones of constructive interference in the microwave to move because the path length of waves being emitted from the microwave source varies. In some such embodiments, a stationary support plate is disposed in the at least one cavity such that a third path length from the at least one waveguide to the support surface is constant with the oscillation. Alternatively, in some embodiments, the support plate oscillates along three dimensional axes such that a first path length from the first waveguide, the second waveguide, or both, to the support plate varies with the oscillation. In some embodiments, at least one of the first or the second waveguide oscillates relative to at least one of the first or the second cavity such that a first path length from the at least one waveguide to a first wall of the at least one cavity and a second path length from the at least one waveguide to a second wall of the at least one cavity varies with the oscillation. And, in some embodiments, at least one of the first and the second cavities comprises at least one flexible wall that oscillates such that a first path length from the first waveguide, the second waveguide, or both, to the flexible wall varies with the oscillation.
Various means for controlling the magnetrons are available. For example, in one embodiment, the microwave oven includes a single controller for both magnetrons. The controller includes one or more hardware processors and hardware memory. The hardware memory stores instructions that, when executed by the hardware processors, operate the first magnetron, the second magnetron, or both. In some such embodiments, operating the first and the second magnetron comprises oscillating power delivery from a single power input between the first and the second magnetron. Additionally, in some such embodiments, the processors are coupled to one user input device for both cavities. The processors know which magnetron to power based on which door was opened or a reflectance pattern of microwaves generated by the first magnetron, the second magnetron, or both. For example, one embodiment includes one or more microwave-sensitive diodes exposed to the first cavity, the second cavity, or both, either together or separately. The diodes are also electrically coupled to the processors. The memory stores a current generated by the diodes when the microwave operates and the cavities are empty. When an object is placed in one of the cavities to be heated, that object absorbs some of the microwaves in the cavity, reducing the amount of reflectance observed by the diodes, and thus reducing the current generated by the diodes. The controller knows, based on the current generated by the diodes, whether a cavity is being used, and even how large and/or dense the object in the microwave is. A method for determining whether an object is in a cavity, and thus whether or not the microwaves should be sent to that cavity, includes sending a microwave pulse into the cavity and detecting, by the diodes, the level of reflectance of the pulse. The method further includes determining, based on the reflectance, whether an object is in the cavity. If an object is in the cavity, microwaves are directed to the cavity to heat the object. If an object is not present, no microwaves are sent.
The figures described below disclose the microwave oven described above, including the various embodiments, in enough detail to enable one of skill in the art of microwave ovens to make and/or use the microwave oven claimed herein.
First cavity 501 and second cavity 502 are constructed similar to other microwave oven cavities typical in the industry. Thus, the walls are reflective to microwaves, and are capable of withstanding temperatures typically reached in microwave ovens. Additionally, the walls are designed to withstand steam accumulation and heat transfer, and, in some embodiments, are non-stick, and thus can be easily cleaned. For example, in some embodiments, standard commercially-available microwave oven paint is used to coat the interior walls of first cavity 501 and second cavity 502.
In some embodiments, first cavity 501 and second cavity 502 are constructed from a single cavity. In such embodiments, a single cavity is formed, and barrier 503 is placed inside the single cavity, thereby forming first cavity 501 and second cavity 502. In other embodiments, first cavity 501 and second cavity 502 are formed separately, and barrier 503 is formed by adjacent walls of first cavity 501 and second cavity 502. In such embodiments, the walls perpendicular to barrier 503 are segmented, with the segments slideable over each other such that the walls can collapse and expand. For example, in one embodiment, in the first position depicted in
As described above, in some embodiments, barrier 503 is comprised, at least in part, of adjacent walls of the first cavity and the second cavity. Generally, barrier 503 is comprised of materials similar to those comprising the walls of first cavity 501 and second cavity 502. Importantly, in any embodiment, barrier 503 electromagnetically isolates first cavity 501 from second cavity 502 with respect to microwaves. Thus, in some embodiments, barrier 503 includes painted metal, such as steel or aluminum. Additionally, in some embodiments, barrier 503 forms a seal that at least partially thermally isolates first cavity 501 from second cavity 502. For example, in one embodiment, barrier 503 includes a vacuum cavity within a metallic panel. While it is generally understood that absolute thermal isolation is impossible, such an embodiment provides sufficient isolation for the temperatures and time scales experienced in a microwave oven that thermal leaching has a negligible effect on objects being heated in the separate cavities.
In some embodiments where first cavity 501 and second cavity 502 are formed from a single cavity, barrier 503 is supported by notches protruding from the walls of the single cavity. In the same or other embodiments, barrier 503 is held in place magnetically. For example, in some such embodiments, barrier 503 includes permanent magnets disposed within barrier 503 along the outside edges of barrier 503, such as by gluing the magnets to the wall with heat-resistant and/or heat-cured glue. The walls of the single cavity include corresponding magnets outside the cavity positioned on the wall where barrier 503 is to be secured. In one embodiment, the magnets of barrier 503 and the single cavity are aligned north-to-south. In another embodiment, the magnets are aligned north-to-north or south-to-south. In such an embodiment, it is also occasionally beneficial to include sets of magnets mounted to the wall and spaced apart such that the magnets in barrier 503 fit between the wall magnets.
Door 504 is comprised, on a side of door 504 facing towards first cavity 501 and second cavity 502, materials similar to those forming the cavities, and on a side of door 504 facing away from the cavities, any of a variety of materials, such as stainless steel, aluminum, or plastic, to name a few. Generally, door 504 is comprised of materials commonly used in manufacturing microwave oven doors. Door 504 includes viewing port 504a, which is generally formed of a glass or microwave-safe plastic material having metal strands running through the glass or plastic to reflect microwaves. Door 504 is, in various embodiments, secured by a detent or an electromagnet. For example, in the depicted embodiment, door 504 is electromagnetically latched closed. A permanent magnet is installed in door 504, and a corresponding electromagnet and weak permanent magnet are installed in the body of microwave oven 500. When a user presses the “OPEN” button on control panel 505, the direction of the current running through the electromagnet is switched momentarily (for up to 2-3 seconds in some cases), reversing the direction of the magnetic field generated by the electromagnet. The reverse magnetic field is stronger than the force generated by the magnetic fields of the permanent magnets in door 504 and the body, and forces door 504 open.
Control panel 505 is, generally, an interface that allows the user to interact with processors and memory that control operation of microwave oven 500. In some embodiments, control panel 505 is a graphical user interface displayed on a touchscreen. In other embodiments, control panel 505 includes one or more push buttons. In yet other embodiments, control panel 505 includes permanent markings on or over a touchscreen.
The hardware processors and memory store instructions for operating microwave oven 500. In various embodiments, those instructions include identifying which cavity is desired for use, identifying a power level either desired or necessary, identifying an amount of time needed for cooking, and delivering power to the appropriate magnetron. In some embodiments, some or all of these steps are automated. For example, in one embodiment, microwave oven 500 includes diodes corresponding to each cavity. The processors use the diodes to determine which cavity contains an object or objects to be heated and powers the corresponding magnetrons accordingly.
Housing 506 is comprised of any of a variety of materials typical for microwave ovens, and includes various metals and/or plastics. At least a portion of housing 506 is metal to provide grounding for the electronics that power microwave oven 500. Generally, housing 506 is sturdy enough to provide structural support for one or more of the magnetrons, power transformers, first cavity 501, and second cavity 502.
In some embodiments, the hardware controller determines which cavity to provide power to based on which door was most recently opened or closed. In such embodiments, each door includes a switch that is closed when the door is closed and opened when the door opens. One such switch is a magnetic switch, such as that described above with regard to
Barrier 603 is depicted in
In some embodiments, door 604 and door 605 open in the same direction, such as to the right, downwards, or upwards. In embodiments where both doors open downwards or upwards, it is occasionally beneficial to lock door 604 closed as barrier 603 is in the second position. In other embodiments, door 604 and door 605 open in opposite directions. For example, in one such embodiment, door 604 opens downwards and door 605 opens upwards. In some cases of such an embodiment, door 604 and/or door 605 include pneumatic, hydraulic, or spring-loaded articulators that support the doors in the open position and prevent the doors form slamming closed. In another embodiment where the doors open in opposite directions, door 604 opens downwards and door 605 opens upwards.
As used herein, the direction of opening, such as “right,” “left,” “up,” or “down” refers to a direction of rotation about a pivot point on the door. The pivot point is, in many cases, closest to the directionally-indicated edge of the door. For example, a door that opens to the right pivots at it's right-most edge, with the left edge swinging around the pivot point in a clockwise manner towards the right.
The magnetrons, antennas, and waveguides are, in various embodiments, similar or identical to those commonly used in existing microwaves. However, in some embodiments, the waveguides are excluded, such that the antennas extend into the cavities. In such embodiments, the antennas are shielded from the cavities by a microwave-transparent housing to protect the antennas from exposure to food, liquid, and/or steam that all too often finds its way to the walls of microwave oven cooking cavities.
Oscillator 1210 includes motor 1210a, collar 1210b, foot 1210c, and mounting bolt 1210d. Motor 1210a is fixedly coupled to housing 1200a, and rotates a shaft fixedly coupled to foot 1210c (the shaft similar to shaft 1102 described above). Foot 1210c is rotatably coupled to, in the depicted embodiment, a wall of cavity 1202 by bolt 1210d. As shown, bolt 1210d is off-center between the two cavities, which enables oscillation back-and-forth and left-to right. As motor 1210a rotates footing 1210c, collar 1210b and the off-center coupling of foot 1210c to the cavities causes the cavities to oscillate with respect to housing 1200a, and those components fixed to it, up-and-down, left-to-right, and back-and forth.
In some embodiments, oscillator 1210 rotates in a continuous fashion. In other embodiments, a controller for microwave 1200 (similar to those described above) includes instructions for powering the motor that varies the speed and direction of the oscillation, either based on a desired cooking setting, time, and/or level, or during cooking to account for variability of zones of constructive interference within the microwave.
| Number | Name | Date | Kind |
|---|---|---|---|
| 7087872 | Dobie | Aug 2006 | B1 |
| 20080087662 | Takizaki | Apr 2008 | A1 |
| 20130153570 | Carlsson | Jun 2013 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20180152991 A1 | May 2018 | US |
