My invention generally pertains to a microwave oven having a rotating turntable to enhance uniformity of cooking food. More particularly my invention relates to convenience and enabling a safe removal of cooked food from the microwave oven once the cook cycle has ended. My invention discusses an advantage for attaining an uniform food item placement and removal consideration, where the turntable parks at the end of the cook cycle leaving the food in about the same physical position as where it was placed at the beginning of the cook cycle. A conveniently repeated food item emplacement and removal location contributes to less chance for spillage or dropping of the food item upon being lifted from the oven.
In this invention's operating scenario, a food item is placed on a rotating turntable having a finite circumvolution time period. A preferred cook time is selected for the food item and compared with the circumvolution time period. In the most simplistically illustrative terms, the cook time is subtracted from the circumvolution time period and the difference time period is subsequently used as a delay time interval. The delay time interval postpones the onset of the preferred cook time cycle while an immediate start of the circumvolution time period, or turntable rotation commences. In other words, the turntable starts turning and the preferred cook time waits until the turntable position measurably advances. As a result when the preferred cook time cycle commences both the circumvolution time period and the preferred cook time will have a concurrent end-point. The food item will then be positioned at the same situs as it was at the onset of the oven's operation. The cooking and turntable will stop at the same moment without delay between the cooking end-point and the turntable stoppage.
My invention affords a superior degree of safety and convenience in removing heated food from a microwave oven by reinstating the turntable's start-position as a park-position concurrent with a completion of a microwave heating cycle used to heat or cook food and similar items.
As is well known and taught by Kang in U.S. Pat. No. 5,558,799 the turntable in many microwave ovens may stop in a random position and this can result in problems when taking food out of the microwave oven. ('799 Kang, col. 1, lines 52-58). However, what Kang offers is to start the microwave cooking and the turntable rotation at the same time. The cooking proceeds for a period of time and stops. The turntable may be in a random position at this instant, but it is programmed to continue rotation until it returns to about the same position that it was in when the food was placed into the microwave oven. As a result, considerable variation in time may occur between completion of cooking and the moment when the door may be opened to retrieve the food. In a typical microwave oven having a 3-rpm rate, the circumvolutional time period is 20-seconds. Therefore, if a food item is placed in the oven for a 30-second warm-up, the '799 teaching stops-cooking about 10 seconds into the second turntable rotation and the turntable will continue to rotate for 20 additional seconds before the food is removable.
In another U.S. Pat. No. 5,440,105 Kim teaches a similar microwave oven operation in which the heating and the turntable rotation begin together ('105 Col. 3, Lines 36-39), the cooking cycle completes ('105 Col. 4, Line 5) and “the turntable continues to be rotated” ('105 Col. 4, Lines 17-18); also said in claim 1 para. F (and G). In other words, although cooking has finished, the food remains in the microwave for a considerable length of time before it may be conveniently removed.
The main goal and hence the main benefit to a user of my invention pertains to parking the turntable of a microwave always in the same position. The concept is to afford the user considerable advancement in convenience and perhaps even more importantly, safety. The safety aspect lays in the repositioning of a dish or other foodstuff arrangement in a predictable position similar to what it was in when the cook cycle began. As is well know, prior art microwave ovens (with turntables) often leave the foodstuff in awkward positions, or in a rearward location on the turntable. This makes reaching into the microwave and handling a hot dish or food item a difficult if not hurtful experience.
A majority of microwave ovens known in the art simply time the cook cycle and shut-off. Usually this means the microwave magnetron, the turntable rotation motor and even the interior light simply shut-off. The food item sits on the turntable in any of an unlimited number of angular locations.
As was mentioned previously, some advancement is offered by others (Kang '799 and Kim '105, for example) where the microwave cooking is timed to completion with the turntable and the cooking sequence starting together. When the cooking stops, the turntable continues rotating until it reaches the original situs and then it stops. While this is improvement over random parking, it may cause a cook to experience angst because he/she “knows” the cooking has stopped, but the foodstuff is still “stuck” in the oven for another few to many seconds before removal is convenient. To the fastidious cook or chef this unpredictable wait is unacceptable and even to a common cook, the wait after cooking completes may be aggravating. What this leads to is a forced opening of the door and removal of the food item from whatever position it assumes when the door is cracked.
A more pleasant cooking experience is brought forth by my invention where the onset of cooking is slightly delayed relative to onset of turntable rotation. This delay is determined to the extent necessary to deliver the end of the cooking cycle and the original situs parking for the turntable. As a result, even the most fastidious cook or chef is able to remove the food item immediately when cooking stops. Moreover, the turntable is re-parked in its original situs for safety and convenience.
A new level of convenience and safety is afforded the user of a microwave oven by my invention's novel teaching. In a most simple summation for my invention, a food item is placed on a rotating turntable, the oven is set to heat for a random period of time, the turntable starts at a fixed rotational rate, the cooking is slightly delayed to commence when the rotation of the turntable has reached an angular position such that when the overall cook period completes the turntable has returned to its original situs some integer of 360 degrees from the initial food placement event.
The turntable operates at 3-RPM having a circumvolution time period of 20-seconds. This interprets that a food item set to cook for 1½ minutes (90-seconds) will result in 4½ rotations of the turntable. Hence in my invention the onset of the 90 second cook period is delayed by 10 seconds after the door is closed the turntable is rotating ½ turn. As a result, the turntable will assume a full 5 rotations when the cooking completes, leaving the food item conveniently “out in front” for easy removal.
A food item is placed on the 3-RPM turntable and set to heat for 10-seconds, or 180 degrees turntable rotation. This invention recognizes time factors and as a result, the turntable and cooking may commence together, the turntable rotates 90-degrees whereupon it reverses and returns 90-degrees re-parking in its original situs when the heating cycle ends. For the heating of an item with a cooking time of less than the time of a 180 degree turntable rotation (e.g., less than 10 seconds in this cited example) the mentioned cycle reversal is believed to be a most efficient method for obtaining the desired turntable re-parking results.
When the desired heating time is fractionated to the extent where the cook time represents 90 degrees or less of overall turntable rotation, my finding suggest that it is advantageous to rotate the cook item on the turntable for the cook-time (say, 7-seconds) with the heating turned OFF. Then the turntable is reversed and the heating is turned ON, with the turntable returning to it's original position after 7-seconds of cooking (albeit, with 14-seconds of overall elapsed time). My finding is that with heating times of less than about 90-degrees rotation or else less than about 10 seconds duration are most accurately determined by this methodology. In usage, such brief cook-times are often used to slightly warm a slice of bread, soften peanut butter or other such minimalistic heating needs.
The average speed of the turntable is variously controlled in order to assure congruity between the end-point stoppage of the turntable and the completion of the cook-cycle whereby the turntable ends-up parking in substantially the same position as what it started operating from. The intent is to allow convenient and safe emplacement and removal of cookable food items by returning the item to the starting-point upon completion of the cook cycle.
What this Invention “is” and “is-not”
This invention “is not” about merely completing a rotational cycle of a turntable irrespective of when an associated cooking event may have timed-out. It furthermore is not about shutting off the microwave source while the food item is nowhere near the original situs and then advancing the turntable until it re-parks near the original situs.
This invention “is” about creating end-point coincidence between a timed heating period and a food-bearing turntable's circumvolution time period by delaying onset of the timed heating period by an amount equated as the difference between the timed heating period and an integral number of turntable circumvolational events. The invention “is” about enabling presentation of the cooked food item in the same turntable positional location for both emplacement and removal. The intent is to allow user access for removal of a heated item with consistent convenience and safety.
My invention is depicted by 18 sheets of drawings showing 18 figures, including:
FIG. 1—An overall view of a microwave oven including this invention.
FIG. 2—A graphical representation of the operation for the oven depicted in
FIG. 3—An alternative turntable drive method depicting my invention.
FIG. 4—A graph representing the operation for the turntable shown in
FIG. 5—A different approach for a turntable driven in accord with the central object of my invention.
FIG. 6—A graph showing the events satisfied by the turntable drive of
FIG. 7—A turntable with the onset of cook-power delayed to allow turntable to align itself with the door at the end of the cook cycle.
FIG. 8—A graph depicting the delay of the cook cycle onset.
FIG. 9—A BASIC Computer Program assisting in the defining of prefatory delay of cook-time onset.
FIG. 10—A turntable arrangement with initial reversal to synchronize the turntable with the cook time.
FIG. 11—Graph depicting the turntable performance of
FIG. 12—Rudimentary schematic for a microwave oven including turntable reversal to synchronize the turntable's end-of-cycle park position with the turntable's initial position.
FIG. 13—Turntable that runs at two different radial rates during the cook cycle to produce a full 360° rotation during the cook cycle.
FIG. 14—Graphical representation of the turntable running normal and then speeded-up; plus conversely showing initially sped-up and then returning to normal speed.
FIG. 15—Turntable that “speeds up” mid-cycle to enable turntable to reach it's park position at the end of the cook cycle.
FIG. 16—Graphical presentation showing the mid-cycle turntable speed-up depicted in
FIG. 17—Turntable embodiment that changes speed to speed-up for short cook cycles and slow-down for longer cook cycles, so as to bring the food to the start position at the end of the cook cycle.
FIG. 18—Microwave oven embodiment providing for variable speed turntable operation as described in
A microwave oven layout is depicted in
As presently illustrated, the preferred cook time is set for 24-seconds. The cookable food item is positioned frontward, as depicted by the reference line 60-1. When cooking commences, the turntable rotates counterclockwise 100-1 for 12-seconds and reverses direction, next rotating clockwise 100-2 for an additional 12-seconds, accumulating a total of 24-seconds of cook time exposure to the microwave energy 32. The bidirectional motion of the turntable returns the foodstuff 50 to about the same position 62-1 from which it originated 60-1.
A graphical representation of the operation of the turntable associated with
Under circumstances where the preferred cook time is substantially less that the 360 degree turntable rotation time, a variant sequence of events as depicted in
Better yet,
In event the cook time is of more lengthy duration, say 85-seconds as shown now in
The graphical representation of
Another variant control for the turntable is now depicted in
A graphical representation of
A computer program shown in
A rudimentary schematic for a microwave oven encompassing my invention's contributions appears in
Advancing to
With
With
In
Practice Caveats
A reasonable and comprehensive effort has been made to explain this invention in a manner which enables a person of modest skill in the art to efficiently duplicate my findings. The utter essence of my invention is to absolutely and remarkably repark a microwave oven's turntable in the same position as it assumed when foodstuff was placed upon the turntable. Moreover, the turntable rotation and the cooking are synchronized to the extent that cooking is completed concurrent with the foodstuff having reached the desired reparking situs. The endpoint congruency is novel in being attained by time-delaying the start of the cooking cycle to usually occur moments after the start of the turntable's rotational cycle to allow the physical motion to achieve a head-start relative to the cook-time. This offset between the two functional cycles allows the end-point concurrence to reliably be achieved. Convenience is honored by permitting immediate removal of the food the instant the cooking ceases and the turntable has reparked.
Other adaptations to obtain my inventions central goal of assured reparking repeatability and congruence between end of rotation and end of cooking power are shown which include changing mid-cycle speed of the turntable and modulating the turntables average rotational speed to agree with the cook cycle duration.
I fully expect that a skilled artisan may develop alternate details for my invention's implementation including a considerable variation regarding physical form details of the microwave oven embodiment and the turntable arrangement. More central to this invention is that a savvy engineer may improvise various microprocessor options and memory configurations as well as software scripts and firmware arrangements to satisfy any of a variety of obvious operational preferences. I say that these are merely technique variants result from mere applied engineering skill coupled with an ever-increasing plethora of options regarding parts, components, techniques and programming skills which may be utilized to duplicate my invention's contribution to the art-field.
Any attempt by another to circumvent the essence of my invention to attain reaching the cook cycle end-point and the reparking of the turntable's endpoint at the same moment to allow prompt removal of the cooked foodstuff item shall be prudently viewed with caution and suspicion. I realize that hindsight cleverness may suggest other physical and technical embodiments exhibiting a difference in operational detail from that which I specifically depict to become readily apparent to and subsequently tried by others. As a consequence to this realization, I challenge that other technical hookups, signal processing logic and physical embodiment variations that satisfy my invention's essence are merely natural and obvious extensions of the invention's central teachings. In particular this broadly includes reparking the microwave oven's turntable in the same location at the end of a cook cycle as what it assumed at the onset of the overall operating cycle. Any scheme which satisfies this objective of my invention conclude the turntable rotation and the cook cycle together must be found as merely obvious engineering refinements, embodiment practices and operational details that are construed to be irrefutably within the scope of my invention as presently taught and inclusively claimed.
Number | Name | Date | Kind |
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4308445 | Offutt | Dec 1981 | A |
4939333 | Sakai et al. | Jul 1990 | A |
5097106 | Arai et al. | Mar 1992 | A |
5440105 | Kim | Aug 1995 | A |
5558799 | Kang | Sep 1996 | A |
Number | Date | Country |
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01003425 | Jan 1989 | JP |
03163791 | Jul 1991 | JP |