CA1169495A - Microwave oven control system - Google Patents
Microwave oven control systemInfo
- Publication number
- CA1169495A CA1169495A CA000381617A CA381617A CA1169495A CA 1169495 A CA1169495 A CA 1169495A CA 000381617 A CA000381617 A CA 000381617A CA 381617 A CA381617 A CA 381617A CA 1169495 A CA1169495 A CA 1169495A
- Authority
- CA
- Canada
- Prior art keywords
- enclosure
- oven
- weight
- digital processor
- microwave oven
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/6447—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors
- H05B6/6464—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors using weight sensors
Abstract
MICROWAVE OVEN CONTROL SYSTEM
Abstract of the Invention A microwave oven having a weight measuring device positioned therein for supporting a food body to be cooked. The sensed weight produces a signal which is supplied to a digital control for the oven. In operation, a food body is placed on the weight measuring device to supply weight data to the control computer and a front panel control is manually programmed to supply data to the computer indicative of the kind of food to be heated in the oven. The com-puter then computes the time required to heat the food body. When the start button is pushed, the computer control energizes the oven and then automatically deenergizes the oven after the computed heating time has elapsed.
Abstract of the Invention A microwave oven having a weight measuring device positioned therein for supporting a food body to be cooked. The sensed weight produces a signal which is supplied to a digital control for the oven. In operation, a food body is placed on the weight measuring device to supply weight data to the control computer and a front panel control is manually programmed to supply data to the computer indicative of the kind of food to be heated in the oven. The com-puter then computes the time required to heat the food body. When the start button is pushed, the computer control energizes the oven and then automatically deenergizes the oven after the computed heating time has elapsed.
Description
~ ~i'3~L~S
Background of the Invention Microwave ovens have used timing systems to automatically control the duration of time of application of microwave energy to a food body in the oven. In addition, the average level of microwave energy applied to the oven has been adjusted for dif-ferent types of food. However, such systems have relied on an estimate of the weight of the food body or have required separately weighing the food body prior to positioning in the oven.
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-Summary of the Invention In accordance with this invention, there is disclosed a weight sensing element positioned beneath a microwave oven and providing support for a food body within the oven enclosure.
~ore specifically, this invention discloses a substantially microwave transparent shelf in the oven supported on a plurality of low microwave loss posts, made for example of ceramic or plastic, which extend through apertures in the bottom of the oven and rest on a weight determining means outside the microwave enclosure. The weight determining means supplies a signal through a variable frequency pulse oscillator 92 to a digital processor 74 through its interface 84 which converts the measured weight to a digital data signal in accordance with well-known practice. The processor 7~ is also supplied digital information from manual input such as touch pads to provide inputs of the kind of food body and the desired cooking conditions for the food body.
In accordance with this invention, the apertures in the bottom of microwave enclosure, through which the microwave trans-parent members supporting the shelf extend, have transverse dimensions substantially less than an effective one-half wavelength at the microwave frequency so that substantially no microwave energy leaks from the microwave enclosure through these apertures.
Sufficient support for shelf 26 with such support posts 28 and ~apertures of a small size can be achieved by providing several spaced posts sufficient support members to carry any desired load while still retaining microwave integrity of the enclosure~
I Further in accordance with this invention, the microwave transparent shelf supporting the food body within the enclosure is spaced from the metallic bottom of the microwave enclosure so that microwave energy is readily coupled through the microwave transparent support shelf into the under side of the food body.
Thus, the weight of the food body may be used to compute the amount of microwave energy to be applied to the food body to achieve a given degree of cooking.
In accordance with this invention, there is provided for energizing the microwave oven enclosure with microwave energy supplied to the microwave oven through a coaxial line energizing a rotating primary radiator within the oven. By positioning the primary radiator in the upper region of the oven and selectively producing radiation into the oven from a plurality of spaced regions having different polarization orientations, a uniform pattern of direct radiation toward the food body can be achieved so that coupling of the energy into the food body becomes substan-tially the same for different locations of the food body on the support shelf. Thus, the cooking achieved by weight programming of the` oven control is the same when the food body at substantially any location in the general central region of the support shelf and will produce substantially the same degree of cooking of a O given food body. Preferably, the support elements~for the shelf are positioned outside the central region o the shelf so that the shelf will be mechanically stable. Also, relatively inexpensive weight sensing means may be positioned beneath the lower surface of the microwave oven enclosure and can be used to produce rela-tlvely accurate electrical signals for input to the data processor control system.
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In accordance with the present invention, there is provided a microwave oven comprising: a conductive enclosure; a magnetron for providing microwave energy to the interior of said enclosure; a tray positioned in said enclosure; a digital processor; means coupled to said tray for generating signals corresponding to weight on said tray, said signals being supplied to said digital processor; an operator actuable control for providing said digital processor with an input corresponding to a food category; an operator actuable control for storing one of said signals in said~digital processor, said one of said signals representing the weight of a food dish by itself being supported on said tray, said digital processor subtracting said one signal from a subsequent signal to provide a value equal to the weight of food inserted in said dish af~er said one of said signals is stored;
a digital display; said digital processor displaying said value on said digital display; and an operator actuable control for activating said magnetron, said digital processor, in response to said magnetron actuating control, calculating a cooking time at least in part as a function of said value and said food category input, displaying said cooking time on said digital display, and controlling said magnetron in accordance with said cooking time while counting down said cooking time on said digital display.
In accordance with another aspect of the invention, there is provided the method of cooking with a microwave oven comprising the steps of: inputting a food category to a digital processor; position-ing a cooking dish in the enclosure of said microwave oven on a supporting tray coupled to a scale outside said enclosure; activating ~ :
an operator actuable control for storing a signal from said scale in said digital processor, said stored signal representing the weight of said dish; positioning said dish with food in it on said tray, said digital processor automatically subtracting said stored signal from a - 3a -9~15 subsequent signal from said scale to provide a value corresponding to the weight of said food; displaying said value on a visual display;
calculating with said digital processor a cooking time period which is at least in part a function of said value and said food category input;
activating an operator actuable control to initiate energizing the magnetron of said microwave oven; displaying said time period on said visual display; and controlling the cooking time on said microwave oven in accordance wi~h said time period while counting down said time period on said visual display. :
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Brief Description of the Drawings Other and further objects and advantages of the invention will become apparent as the description thereof progresses reference being had to the accompanying drawings wherein:
FIG. 1 is a diagram of a microwave oven embodying the invention;
FIG. 2 illustrates a vertical sectional view of a micro-wave oven taken along line 2-2 of FIG. 3 illustrating an em-bodiment of the invention;
FIG. 3 illustrates a vertical sectional view of the em-bodiment of the invention illustrated in FIG. 2 taken along line 3-3 of FIG. 2;
FIG. 4 illustrates a transverse sectional view of the embodiment of FIGS. 2 and 3 taken along line 4-4 of FIG. 2;
FIG. 5 illustrates a vertical sectional view of an alternate embodiment of the invention illustrated in FIG. 1 taken along line 8-8 of FIG. 6;
FIG. 6 illustrates a transverse sectional view of the embodiment of FIG. 5 taken along line 6-6 o FIG. 5;
FIG. 7 illustrates a vertical sectional view of the em-bodiment of the invention illustrated in FIG. 5 taken along line 7-7 of FIG. 6;
FIG. 8 illustrates a transverse sectional view of the em-bodiment of FIG. 5 taken along line 8-8 of FIG. 6;
FIG. 9 illustrates a vertical sectional view of an alternate embodiment of a microwave oven incorporating the invention taken along line 13-13 of FIG. 10;
FIG. 10 ill~strates a transverse sectional view of the em-bodiment of FIG. 9 taken along line 10-10 of FlG. 9;
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FIG. 11 illustrates a vertical sectional view of the em-bodiment of the invention illustrated in FIG. 9 taken along line 11-11 of FIG. 10;
FIG. 12 illustrates a vertical section of the embodiment of FIG. 9 taken along line 12-12 of FIG. 10; and FIG. 13 illustrates a vertical sectional view of the em-bodiment of FIG. 9 taken along line 13-13 of FIG. 10.
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Description of the Preferred E bodiment Referring now to FIG. 1, there is shown a microwave oven l0 of the type disclosed in FIGS. 2-4. The microwave oven 10 has an enclosure 12 and a front control panel 50 which contains touch pads 52-62, 174 and 175 labelled heat units, power level, start, stop reset, zero, dish, weight and cook time respectively whose functions will be described presently. Touch pads 60, 62, 172 and 174 have individual lights 66, 68, 70 and 72 respectively which indicate when the particular touch pad is touched. A digital pro-cessor 74 containing a microprocessor 76, a read only memory 78, a random access memory 80 and an interface 82 is used to control the operation of a high voltage power supply 84 supplying the magnetron 22 whose microwave out-put is supplied via a waveguide 20 and a coaxial feed 16 to a rotating pri-mary radiator 18. The digital processor 74 may be, for example, the "superkim" digital processor manufactured by MICROPRODUCTS of Redondo Beach, California. However, for production economy, a special printed circuit board omitting the unused portions of the "superkim" may be used to save both space and cost. The touch pads of front panel keyboard 50 are connected to the interface 82 in a similar fashion to the conventional "superkim" key-board and data for display of the lights on panel 50 is also supplied through the interface 82.
The support shelf 26 supporting a food body 40 in a dish 176 actuates weight sensor 32 whose output is derived via a photocell 42 responding to a light source 44. The intensity of the light from source 44 which falls on photocell 42 is determined by the amount of movement of a septum 46 actuated by the load on support shelf 26 by posts 28 which extend through apertures 30 in the bottom 24 of enclosure 12. The amount of deflection of septum 46 depends upon the weights of the food body 40, the dish 176, and the shelf 26 acting on the weight sensor 32 against a leaf spring 9~. The output of photocell 42 controls the free running pulse oscillator 92 whose pulse rate output varies between 1,000 and 2,000 pulses per second and preferably varies substan-tially as a linear function of the sensed weight. The output of the oscillator 92 is supplied to the digital processor 74 via the interface 82 which converts the pulse rate to a digital number and directs it to random access memory 80 to be stored.
Referring now to FIGS. 2, 3 and 4 there is shown details of a microwave oven 10 which can be used ïn FIG. 1.- Metallic micro-wave enclosure 12 has an access opening closed by a closure member 14 such as a door. Microwave energy is supplied to oven 10 through coaxial connection 16 extending through an aperture in the top of enclosure 12 and coupled to a rotating primary radiator 18. The central conductor of coaxial line 16 extends into waveguide 20 and supplies the radiator with microwave energy from magnetron 22 at a frequency, for example, of 2450 MHz in accordance with well-known practice. Air from a blower 86 is directed through waveguide 20 and into enclosure 12 to rotate radiator 18.
In accordance with this invention there is positioned above the bottom wall 24 o enclosure 12 a support shel~ 26 made of s ~`~ substantially microwave transparent material such as Pyrex.
Support shelf 26 is supported on four low microwave loss posts 28 which extend through apertures 30 in the bottom wall 24 of enclosure 12. Support posts 28 are rigidly attached to a weight sensing mechanism 32 supported on the bottom of microwave oven 10 while micrawave enclosure 12 is supported, for example, by brackets 34 f~om the side and/or bottom walls of the cabinet 36 of microwave oven 10. Since the posts 28 are rigidly attached to the sensing structure 32 which is rigidly supported by the frame 36 of the oven, lateral motion of the members is prevented.
The support shelf 26 is restricted laterally by ceramic washers 38 glued to the bottom surface of shelf 26 with the support posts 28 extending into the centers of the washers 38. The diameter of apertures 30 is made less than a half wavelength of the frequency of magnetron 22 and preferably is somewhat less than a quarter wavelength thereof so that substantially no micro-wave energy leaks out of enclosure 12 through apertures 30.
~eight sensing element 32 may be a conventional scale element or may be specially designed to supply a digital output indicative of the weight of a load such as a food body 40 supported in enclosure 12 on shelf 26.
The weight sensor 32, as shown herein, has the frame 36 supported on the floor of the cabinet of oven 10. The posts 28 are rigidly connècted to metal kni~e edge elements 154 which rest in V-shaped troughs 156 welded to arms 158. A pair of arms 158 is positioned on each side of the oven with their inner ends con-nected by a tension loop 132 and their outer ends resting via inverted trough portions 162 on knife edge bracket members 164 fixed to the frame 36. The inverted trough members 162 extend respectively at the front and rear of the oven between the arms *`~r6~d~c /v~ --8 -s 158 on each side of the weight sensor 32 so that weight pres-sure on any post is transferred equally to deflect all of the arms 158 via torsion of the inverted trough members 162 and the links 160. A projection on one of the arms 158 presses a leaf spring 94, one end of which is attached to septum 46 and the other end of which is ridigly attached to a block 96 so that the projection 88 on the arm 158 forces the arms upwardly under the sprin~ pressure of the leaf spring 94. When a weight is placed in the oven such as a dish or food body, motion of the posts 28 causes the arms 158 to move downward at their inner ends depres-sing leaf spring 94 and hence depressing septum 46 thereby reducing the light from light 44 which is intercepted by photocell 42.
Since arms 158 and sensing mechanism 32 are removed from the center of oven floor 24, the floor 24 of the oven 10 can be beneath the actual tops of the arms 158 and torsion members 90 so that these members may be sufficiently rugged to transfer the weight to the sensor without interferlng with the bottom 24 of the enclosure 12. Hence, the welght sensing mechanism 32 may be installed within the cabinet 36 of oven lO for existing domestic microwave oven designs.
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_g_ Description of the Preferred Mode of Operation of the Invention In the preferred mode of operation, the equipment, having been turned on, energizes weight sensor 32 and digital processor 74. The touch pad 60 is then touched with the oven empty to zero the equipment. Sensor 32 senses the weight of the shelf 26 in the enclosure 12 and stores a zero number in random access memory 80. During this process, the light 66 lights to indicate that this has been achieved. If a dish 176 is used for the food body 40, the weight of the dish may be separately stored in the memory 80 by pushing the pad 62 labelled "dish". This lights the light 68 and turns off the light 66. The food body 40 may be then placed in the oven with or without a dish since if no dish were used and the pad 62 labelled "dish" were touched, no additional weight would be stored in the memory 80. Weight pad 64 is then touched, and light 70 lights while light 68 goes out.
~he weight will appear at numerical display 98. Touching cook time pad 174 will light light 72 and the required cooking time will appear in the display units 98 for a preselected cook program in read only ~emory 78. This may be, for example, the reheat mode indicated by the lowest of the heat units 25 used for reheat or frozen pastry, as indicated by the light 100 and a power level of 100% as indicated by the light 102. Different heat units may be selected by sequentially pushlng the heat unit pad S2 to cause lights 104-118 to be sequentially turned on one at a time extinguishing the previous lower light. If it is desired to .
reset these lights, touching reset pad 58 will cause the lights to return to their lowest or preset level. Similarly, by touching power level pad 54, the lights 122-130 may be selected sequentially moving the cooking level from high or 100% power to warm or 10%
30 power as indicated by light 128. If pad 50 is touched again, zero -'3~5 power light 130 lights in which case the display indicates time only. In all other locations, as indicated by lights 120-128, the display 98 indicates the computed time required to cook the food body 40 to the desired level. When the start pad 56 is then touched, the cooking proceeds at the selected heat unit level and power level until the appropriate time has elapsed with display 98 continuously showing the remaining cook time.
When the remaining cook time reaches zero, the magnetron 22 is deenergized by deenergizing the power supply 84. Also, an indicator such as an alarm bell, not shown, may be energized to give the operator an audible indication that the cooking program is completed.
I This mode of operation of the unit eliminates cooking errors which might occur by programming in the weight of the food manually since the automatic control of the power supply by a food weight sensed in the oven at the time the start button is pressed prevents inadvertent manual insertion of erroneous data. Thus, it may be seen that any desired program may be stored in the read only memory 78 to provide necessary indications of the start and the 20 stop. In addition, since the lights 100-130 indicate the input to the digital processor program and the computed function is indicated by the light 66-72, the computed result supplied by the microprocessor, as indicated by the display units 98, provides a simple substantially error-free checking mode in which the manually inputted data is indicated by the lights and the digitally processed result is indicated by the display 98.
S3~5 Description of an Alternate Embodiment of the Invention ,~
Referring now to FIGS. 5-8, there is shown an alternate embodiment of an oven having a weight sensor 32 in which torsion members 90 transfer weight from the posts 28 to arms 158 which are connected by separate tension members 132 through a coil spring 134 to a bracket 136 connected to the enclosure 12.
When the food body 40 applies torque to the arms 158, their inner ends are depressed and the septum 46 moves between the photocell 42 and the light source 44 to cause changes in the output of photocell 42.
t~35 Description of a Third Embodiment of the Invention Referring now to FIGS. 9-13, there is shown a still further embodiment of the invention wherein the posts 28 rest on movable frame members 138 which, in turn, are carried by the free ends of a pair of center supported leaf springs 140. Connection of the free ends of springs 140 to the frame members 138 is via adjustable screw members 142 which provide for leveling adjustment of the scale. A central channel member 144 is rigidly connected between the frame members 138 and carries the septum 46 which then moves between light 44 and photocell 42.
Zero adjustment of the unit is provided by supporting light 44 and photocell 42 on a separate support plate 146 which is ad-justably attached to the oven cabinet 36 by screws 148 and springs 150 so that the weight sensor 32 may be zero adjusted.
This completes the description of the embodiments of the invention illustrated herein. However, many modifications thereof will be apparent to persons skilled in the art without departing from the spirit and scope of this invention. For example t a strain gauge could be substituted for the light 44 and photocell element 42, various contours could be used for the edge of the septum 46 and any desired digital processing program could be used. Accordingly, it is contemplated that this invention be not limited to the particular details illustrated herein except as defined by the appended claims.
Background of the Invention Microwave ovens have used timing systems to automatically control the duration of time of application of microwave energy to a food body in the oven. In addition, the average level of microwave energy applied to the oven has been adjusted for dif-ferent types of food. However, such systems have relied on an estimate of the weight of the food body or have required separately weighing the food body prior to positioning in the oven.
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-Summary of the Invention In accordance with this invention, there is disclosed a weight sensing element positioned beneath a microwave oven and providing support for a food body within the oven enclosure.
~ore specifically, this invention discloses a substantially microwave transparent shelf in the oven supported on a plurality of low microwave loss posts, made for example of ceramic or plastic, which extend through apertures in the bottom of the oven and rest on a weight determining means outside the microwave enclosure. The weight determining means supplies a signal through a variable frequency pulse oscillator 92 to a digital processor 74 through its interface 84 which converts the measured weight to a digital data signal in accordance with well-known practice. The processor 7~ is also supplied digital information from manual input such as touch pads to provide inputs of the kind of food body and the desired cooking conditions for the food body.
In accordance with this invention, the apertures in the bottom of microwave enclosure, through which the microwave trans-parent members supporting the shelf extend, have transverse dimensions substantially less than an effective one-half wavelength at the microwave frequency so that substantially no microwave energy leaks from the microwave enclosure through these apertures.
Sufficient support for shelf 26 with such support posts 28 and ~apertures of a small size can be achieved by providing several spaced posts sufficient support members to carry any desired load while still retaining microwave integrity of the enclosure~
I Further in accordance with this invention, the microwave transparent shelf supporting the food body within the enclosure is spaced from the metallic bottom of the microwave enclosure so that microwave energy is readily coupled through the microwave transparent support shelf into the under side of the food body.
Thus, the weight of the food body may be used to compute the amount of microwave energy to be applied to the food body to achieve a given degree of cooking.
In accordance with this invention, there is provided for energizing the microwave oven enclosure with microwave energy supplied to the microwave oven through a coaxial line energizing a rotating primary radiator within the oven. By positioning the primary radiator in the upper region of the oven and selectively producing radiation into the oven from a plurality of spaced regions having different polarization orientations, a uniform pattern of direct radiation toward the food body can be achieved so that coupling of the energy into the food body becomes substan-tially the same for different locations of the food body on the support shelf. Thus, the cooking achieved by weight programming of the` oven control is the same when the food body at substantially any location in the general central region of the support shelf and will produce substantially the same degree of cooking of a O given food body. Preferably, the support elements~for the shelf are positioned outside the central region o the shelf so that the shelf will be mechanically stable. Also, relatively inexpensive weight sensing means may be positioned beneath the lower surface of the microwave oven enclosure and can be used to produce rela-tlvely accurate electrical signals for input to the data processor control system.
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In accordance with the present invention, there is provided a microwave oven comprising: a conductive enclosure; a magnetron for providing microwave energy to the interior of said enclosure; a tray positioned in said enclosure; a digital processor; means coupled to said tray for generating signals corresponding to weight on said tray, said signals being supplied to said digital processor; an operator actuable control for providing said digital processor with an input corresponding to a food category; an operator actuable control for storing one of said signals in said~digital processor, said one of said signals representing the weight of a food dish by itself being supported on said tray, said digital processor subtracting said one signal from a subsequent signal to provide a value equal to the weight of food inserted in said dish af~er said one of said signals is stored;
a digital display; said digital processor displaying said value on said digital display; and an operator actuable control for activating said magnetron, said digital processor, in response to said magnetron actuating control, calculating a cooking time at least in part as a function of said value and said food category input, displaying said cooking time on said digital display, and controlling said magnetron in accordance with said cooking time while counting down said cooking time on said digital display.
In accordance with another aspect of the invention, there is provided the method of cooking with a microwave oven comprising the steps of: inputting a food category to a digital processor; position-ing a cooking dish in the enclosure of said microwave oven on a supporting tray coupled to a scale outside said enclosure; activating ~ :
an operator actuable control for storing a signal from said scale in said digital processor, said stored signal representing the weight of said dish; positioning said dish with food in it on said tray, said digital processor automatically subtracting said stored signal from a - 3a -9~15 subsequent signal from said scale to provide a value corresponding to the weight of said food; displaying said value on a visual display;
calculating with said digital processor a cooking time period which is at least in part a function of said value and said food category input;
activating an operator actuable control to initiate energizing the magnetron of said microwave oven; displaying said time period on said visual display; and controlling the cooking time on said microwave oven in accordance wi~h said time period while counting down said time period on said visual display. :
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Brief Description of the Drawings Other and further objects and advantages of the invention will become apparent as the description thereof progresses reference being had to the accompanying drawings wherein:
FIG. 1 is a diagram of a microwave oven embodying the invention;
FIG. 2 illustrates a vertical sectional view of a micro-wave oven taken along line 2-2 of FIG. 3 illustrating an em-bodiment of the invention;
FIG. 3 illustrates a vertical sectional view of the em-bodiment of the invention illustrated in FIG. 2 taken along line 3-3 of FIG. 2;
FIG. 4 illustrates a transverse sectional view of the embodiment of FIGS. 2 and 3 taken along line 4-4 of FIG. 2;
FIG. 5 illustrates a vertical sectional view of an alternate embodiment of the invention illustrated in FIG. 1 taken along line 8-8 of FIG. 6;
FIG. 6 illustrates a transverse sectional view of the embodiment of FIG. 5 taken along line 6-6 o FIG. 5;
FIG. 7 illustrates a vertical sectional view of the em-bodiment of the invention illustrated in FIG. 5 taken along line 7-7 of FIG. 6;
FIG. 8 illustrates a transverse sectional view of the em-bodiment of FIG. 5 taken along line 8-8 of FIG. 6;
FIG. 9 illustrates a vertical sectional view of an alternate embodiment of a microwave oven incorporating the invention taken along line 13-13 of FIG. 10;
FIG. 10 ill~strates a transverse sectional view of the em-bodiment of FIG. 9 taken along line 10-10 of FlG. 9;
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FIG. 11 illustrates a vertical sectional view of the em-bodiment of the invention illustrated in FIG. 9 taken along line 11-11 of FIG. 10;
FIG. 12 illustrates a vertical section of the embodiment of FIG. 9 taken along line 12-12 of FIG. 10; and FIG. 13 illustrates a vertical sectional view of the em-bodiment of FIG. 9 taken along line 13-13 of FIG. 10.
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Description of the Preferred E bodiment Referring now to FIG. 1, there is shown a microwave oven l0 of the type disclosed in FIGS. 2-4. The microwave oven 10 has an enclosure 12 and a front control panel 50 which contains touch pads 52-62, 174 and 175 labelled heat units, power level, start, stop reset, zero, dish, weight and cook time respectively whose functions will be described presently. Touch pads 60, 62, 172 and 174 have individual lights 66, 68, 70 and 72 respectively which indicate when the particular touch pad is touched. A digital pro-cessor 74 containing a microprocessor 76, a read only memory 78, a random access memory 80 and an interface 82 is used to control the operation of a high voltage power supply 84 supplying the magnetron 22 whose microwave out-put is supplied via a waveguide 20 and a coaxial feed 16 to a rotating pri-mary radiator 18. The digital processor 74 may be, for example, the "superkim" digital processor manufactured by MICROPRODUCTS of Redondo Beach, California. However, for production economy, a special printed circuit board omitting the unused portions of the "superkim" may be used to save both space and cost. The touch pads of front panel keyboard 50 are connected to the interface 82 in a similar fashion to the conventional "superkim" key-board and data for display of the lights on panel 50 is also supplied through the interface 82.
The support shelf 26 supporting a food body 40 in a dish 176 actuates weight sensor 32 whose output is derived via a photocell 42 responding to a light source 44. The intensity of the light from source 44 which falls on photocell 42 is determined by the amount of movement of a septum 46 actuated by the load on support shelf 26 by posts 28 which extend through apertures 30 in the bottom 24 of enclosure 12. The amount of deflection of septum 46 depends upon the weights of the food body 40, the dish 176, and the shelf 26 acting on the weight sensor 32 against a leaf spring 9~. The output of photocell 42 controls the free running pulse oscillator 92 whose pulse rate output varies between 1,000 and 2,000 pulses per second and preferably varies substan-tially as a linear function of the sensed weight. The output of the oscillator 92 is supplied to the digital processor 74 via the interface 82 which converts the pulse rate to a digital number and directs it to random access memory 80 to be stored.
Referring now to FIGS. 2, 3 and 4 there is shown details of a microwave oven 10 which can be used ïn FIG. 1.- Metallic micro-wave enclosure 12 has an access opening closed by a closure member 14 such as a door. Microwave energy is supplied to oven 10 through coaxial connection 16 extending through an aperture in the top of enclosure 12 and coupled to a rotating primary radiator 18. The central conductor of coaxial line 16 extends into waveguide 20 and supplies the radiator with microwave energy from magnetron 22 at a frequency, for example, of 2450 MHz in accordance with well-known practice. Air from a blower 86 is directed through waveguide 20 and into enclosure 12 to rotate radiator 18.
In accordance with this invention there is positioned above the bottom wall 24 o enclosure 12 a support shel~ 26 made of s ~`~ substantially microwave transparent material such as Pyrex.
Support shelf 26 is supported on four low microwave loss posts 28 which extend through apertures 30 in the bottom wall 24 of enclosure 12. Support posts 28 are rigidly attached to a weight sensing mechanism 32 supported on the bottom of microwave oven 10 while micrawave enclosure 12 is supported, for example, by brackets 34 f~om the side and/or bottom walls of the cabinet 36 of microwave oven 10. Since the posts 28 are rigidly attached to the sensing structure 32 which is rigidly supported by the frame 36 of the oven, lateral motion of the members is prevented.
The support shelf 26 is restricted laterally by ceramic washers 38 glued to the bottom surface of shelf 26 with the support posts 28 extending into the centers of the washers 38. The diameter of apertures 30 is made less than a half wavelength of the frequency of magnetron 22 and preferably is somewhat less than a quarter wavelength thereof so that substantially no micro-wave energy leaks out of enclosure 12 through apertures 30.
~eight sensing element 32 may be a conventional scale element or may be specially designed to supply a digital output indicative of the weight of a load such as a food body 40 supported in enclosure 12 on shelf 26.
The weight sensor 32, as shown herein, has the frame 36 supported on the floor of the cabinet of oven 10. The posts 28 are rigidly connècted to metal kni~e edge elements 154 which rest in V-shaped troughs 156 welded to arms 158. A pair of arms 158 is positioned on each side of the oven with their inner ends con-nected by a tension loop 132 and their outer ends resting via inverted trough portions 162 on knife edge bracket members 164 fixed to the frame 36. The inverted trough members 162 extend respectively at the front and rear of the oven between the arms *`~r6~d~c /v~ --8 -s 158 on each side of the weight sensor 32 so that weight pres-sure on any post is transferred equally to deflect all of the arms 158 via torsion of the inverted trough members 162 and the links 160. A projection on one of the arms 158 presses a leaf spring 94, one end of which is attached to septum 46 and the other end of which is ridigly attached to a block 96 so that the projection 88 on the arm 158 forces the arms upwardly under the sprin~ pressure of the leaf spring 94. When a weight is placed in the oven such as a dish or food body, motion of the posts 28 causes the arms 158 to move downward at their inner ends depres-sing leaf spring 94 and hence depressing septum 46 thereby reducing the light from light 44 which is intercepted by photocell 42.
Since arms 158 and sensing mechanism 32 are removed from the center of oven floor 24, the floor 24 of the oven 10 can be beneath the actual tops of the arms 158 and torsion members 90 so that these members may be sufficiently rugged to transfer the weight to the sensor without interferlng with the bottom 24 of the enclosure 12. Hence, the welght sensing mechanism 32 may be installed within the cabinet 36 of oven lO for existing domestic microwave oven designs.
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:
_g_ Description of the Preferred Mode of Operation of the Invention In the preferred mode of operation, the equipment, having been turned on, energizes weight sensor 32 and digital processor 74. The touch pad 60 is then touched with the oven empty to zero the equipment. Sensor 32 senses the weight of the shelf 26 in the enclosure 12 and stores a zero number in random access memory 80. During this process, the light 66 lights to indicate that this has been achieved. If a dish 176 is used for the food body 40, the weight of the dish may be separately stored in the memory 80 by pushing the pad 62 labelled "dish". This lights the light 68 and turns off the light 66. The food body 40 may be then placed in the oven with or without a dish since if no dish were used and the pad 62 labelled "dish" were touched, no additional weight would be stored in the memory 80. Weight pad 64 is then touched, and light 70 lights while light 68 goes out.
~he weight will appear at numerical display 98. Touching cook time pad 174 will light light 72 and the required cooking time will appear in the display units 98 for a preselected cook program in read only ~emory 78. This may be, for example, the reheat mode indicated by the lowest of the heat units 25 used for reheat or frozen pastry, as indicated by the light 100 and a power level of 100% as indicated by the light 102. Different heat units may be selected by sequentially pushlng the heat unit pad S2 to cause lights 104-118 to be sequentially turned on one at a time extinguishing the previous lower light. If it is desired to .
reset these lights, touching reset pad 58 will cause the lights to return to their lowest or preset level. Similarly, by touching power level pad 54, the lights 122-130 may be selected sequentially moving the cooking level from high or 100% power to warm or 10%
30 power as indicated by light 128. If pad 50 is touched again, zero -'3~5 power light 130 lights in which case the display indicates time only. In all other locations, as indicated by lights 120-128, the display 98 indicates the computed time required to cook the food body 40 to the desired level. When the start pad 56 is then touched, the cooking proceeds at the selected heat unit level and power level until the appropriate time has elapsed with display 98 continuously showing the remaining cook time.
When the remaining cook time reaches zero, the magnetron 22 is deenergized by deenergizing the power supply 84. Also, an indicator such as an alarm bell, not shown, may be energized to give the operator an audible indication that the cooking program is completed.
I This mode of operation of the unit eliminates cooking errors which might occur by programming in the weight of the food manually since the automatic control of the power supply by a food weight sensed in the oven at the time the start button is pressed prevents inadvertent manual insertion of erroneous data. Thus, it may be seen that any desired program may be stored in the read only memory 78 to provide necessary indications of the start and the 20 stop. In addition, since the lights 100-130 indicate the input to the digital processor program and the computed function is indicated by the light 66-72, the computed result supplied by the microprocessor, as indicated by the display units 98, provides a simple substantially error-free checking mode in which the manually inputted data is indicated by the lights and the digitally processed result is indicated by the display 98.
S3~5 Description of an Alternate Embodiment of the Invention ,~
Referring now to FIGS. 5-8, there is shown an alternate embodiment of an oven having a weight sensor 32 in which torsion members 90 transfer weight from the posts 28 to arms 158 which are connected by separate tension members 132 through a coil spring 134 to a bracket 136 connected to the enclosure 12.
When the food body 40 applies torque to the arms 158, their inner ends are depressed and the septum 46 moves between the photocell 42 and the light source 44 to cause changes in the output of photocell 42.
t~35 Description of a Third Embodiment of the Invention Referring now to FIGS. 9-13, there is shown a still further embodiment of the invention wherein the posts 28 rest on movable frame members 138 which, in turn, are carried by the free ends of a pair of center supported leaf springs 140. Connection of the free ends of springs 140 to the frame members 138 is via adjustable screw members 142 which provide for leveling adjustment of the scale. A central channel member 144 is rigidly connected between the frame members 138 and carries the septum 46 which then moves between light 44 and photocell 42.
Zero adjustment of the unit is provided by supporting light 44 and photocell 42 on a separate support plate 146 which is ad-justably attached to the oven cabinet 36 by screws 148 and springs 150 so that the weight sensor 32 may be zero adjusted.
This completes the description of the embodiments of the invention illustrated herein. However, many modifications thereof will be apparent to persons skilled in the art without departing from the spirit and scope of this invention. For example t a strain gauge could be substituted for the light 44 and photocell element 42, various contours could be used for the edge of the septum 46 and any desired digital processing program could be used. Accordingly, it is contemplated that this invention be not limited to the particular details illustrated herein except as defined by the appended claims.
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A microwave oven comprising:
a conductive enclosure;
a magnetron for providing microwave energy to the interior of said enclosure;
a tray positioned in said enclosure;
a digital processor;
means coupled to said tray for generating signals correspond-ing to weight on said tray, said signals being supplied to said digital processor;
an operator actuable control for providing said digital processor with an input corresponding to a food category;
an operator actuable control for storing one of said signals in said digital processor, said one of said signals representing the weight of a food dish by itself being supported on said tray, said digital processor subtracting said one signal from a subsequent signal to provide a value equal to the weight of food inserted in said dish after said one of said signals is stored;
a digital display;
said digital processor displaying said value on said digital display; and an operator actuable control for activating said magnetron, said digital processor, in response to said magnetron actuating control, calculating a cooking time at least in part as a function of said value and said food category input, displaying said cooking time on said digital display, and controlling said magnetron in accordance with said cooking time while counting down said cooking time on said digital display.
a conductive enclosure;
a magnetron for providing microwave energy to the interior of said enclosure;
a tray positioned in said enclosure;
a digital processor;
means coupled to said tray for generating signals correspond-ing to weight on said tray, said signals being supplied to said digital processor;
an operator actuable control for providing said digital processor with an input corresponding to a food category;
an operator actuable control for storing one of said signals in said digital processor, said one of said signals representing the weight of a food dish by itself being supported on said tray, said digital processor subtracting said one signal from a subsequent signal to provide a value equal to the weight of food inserted in said dish after said one of said signals is stored;
a digital display;
said digital processor displaying said value on said digital display; and an operator actuable control for activating said magnetron, said digital processor, in response to said magnetron actuating control, calculating a cooking time at least in part as a function of said value and said food category input, displaying said cooking time on said digital display, and controlling said magnetron in accordance with said cooking time while counting down said cooking time on said digital display.
2. The method of cooking with a microwave oven comprising the steps of:
inputting a food category to a digital processor;
positioning a cooking dish in the enclosure of said micro-wave oven on a supporting tray coupled to a scale outside said enclosure;
activating an operator actuable control for storing a signal from said scale in said digital processor, said stored signal rep-resenting the weight of said dish;
positioning said dish with food in it on said tray, said digital processor automatically subtracting said stored signal from a subsequent signal from said scale to provide a value corresponding to the weight of said food;
displaying said value on a visual display;
calculating with said digital processor a cooking time period which is at least in part a function of said value and said food category input;
activating an operator actuable control to initiate energiz-ing the magnetron of said microwave oven;
displaying said time period on said visual display; and controlling the cooking time of said microwave oven in accordance with said time period while counting down said time period on said visual display.
inputting a food category to a digital processor;
positioning a cooking dish in the enclosure of said micro-wave oven on a supporting tray coupled to a scale outside said enclosure;
activating an operator actuable control for storing a signal from said scale in said digital processor, said stored signal rep-resenting the weight of said dish;
positioning said dish with food in it on said tray, said digital processor automatically subtracting said stored signal from a subsequent signal from said scale to provide a value corresponding to the weight of said food;
displaying said value on a visual display;
calculating with said digital processor a cooking time period which is at least in part a function of said value and said food category input;
activating an operator actuable control to initiate energiz-ing the magnetron of said microwave oven;
displaying said time period on said visual display; and controlling the cooking time of said microwave oven in accordance with said time period while counting down said time period on said visual display.
3. The combination in accordance with Claim 2 wherein:
the maximum transverse dimensions of said apertures is less than an effective one-half a free space wavelength of said microwave energy.
the maximum transverse dimensions of said apertures is less than an effective one-half a free space wavelength of said microwave energy.
4. The combination in accordance with Claim 1 wherein:
said weight sensing means comprises means for varying said signals as a function of the weight carried by said load supporting means within said enclosure.
said weight sensing means comprises means for varying said signals as a function of the weight carried by said load supporting means within said enclosure.
5. The combination in accordance with Claim 1 wherein:
said radiating means comprises a rotating primary radiator sup-plied by a coaxial line whose central conductor extends through the upper wall of said enclosure.
said radiating means comprises a rotating primary radiator sup-plied by a coaxial line whose central conductor extends through the upper wall of said enclosure.
6. A microwave oven comprising:
a conductive enclosure having an access opening and a closure member; and means for supplying microwave energy to a rotating radiator in said enclosure comprising a source of microwave energy supplying said radiator and supplied from a source of alternating current through a digitally controlled power supply whose digital control input is supplied by signals derived from a weight sensor positioned outside said enclosure and actuated by a load supporting member supporting a load within said enclosure.
a conductive enclosure having an access opening and a closure member; and means for supplying microwave energy to a rotating radiator in said enclosure comprising a source of microwave energy supplying said radiator and supplied from a source of alternating current through a digitally controlled power supply whose digital control input is supplied by signals derived from a weight sensor positioned outside said enclosure and actuated by a load supporting member supporting a load within said enclosure.
7. The microwave oven in accordance with Claim 6 wherein:
said load supporting member is substantially transparent to microwave energy.
said load supporting member is substantially transparent to microwave energy.
8. The microwave oven in accordance with Claim 6 wherein:
said load supporting member is mechanically coupled to said weight sensor through a plurality of posts extending through apertures in the bottom wall of said oven.
said load supporting member is mechanically coupled to said weight sensor through a plurality of posts extending through apertures in the bottom wall of said oven.
9. The microwave oven in accordance with Claim 8 wherein:
the maximum transverse dimensions of said apertures are less than one-half of a free space wavelength of the microwave energy supplied to said enclosure.
the maximum transverse dimensions of said apertures are less than one-half of a free space wavelength of the microwave energy supplied to said enclosure.
10. The microwave oven in accordance with Claim 6 wherein:
said radiator radiates a plurality of different patterns of microwave energy toward said oven acting as radiating regions toward said load positioned on said load supporting means.
said radiator radiates a plurality of different patterns of microwave energy toward said oven acting as radiating regions toward said load positioned on said load supporting means.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US18989080A | 1980-09-24 | 1980-09-24 | |
| US189,890 | 1994-01-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1169495A true CA1169495A (en) | 1984-06-19 |
Family
ID=22699188
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000381617A Expired CA1169495A (en) | 1980-09-24 | 1981-07-13 | Microwave oven control system |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5784588A (en) |
| CA (1) | CA1169495A (en) |
| DE (1) | DE3138025A1 (en) |
| GB (1) | GB2084436B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4595827A (en) * | 1984-05-02 | 1986-06-17 | Matsushita Electric Industrial Co., Ltd. | Cooking apparatus with weighing device |
| JPS60258895A (en) * | 1984-06-04 | 1985-12-20 | 松下電器産業株式会社 | High frequency heater |
| GB2171580B (en) * | 1985-02-19 | 1988-02-17 | Microwave Ovens Ltd | Stand for use in a microwave oven |
| GB2173902B (en) * | 1985-04-16 | 1988-12-21 | Sharp Kk | Food weight measuring device for cooking appliance |
| US4591684A (en) * | 1985-04-16 | 1986-05-27 | Sharp Kabushiki Kaisha | Cooking completion detection in a cooking appliance |
| JPH05256458A (en) * | 1992-03-13 | 1993-10-05 | Toshiba Corp | Heating cooker |
| US5345068A (en) * | 1992-04-20 | 1994-09-06 | Hitachi Hometec, Ltd. | Cooking oven with rotatable and horizontally movable turntable |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4840496A (en) * | 1971-09-23 | 1973-06-14 | ||
| JPS54156246A (en) * | 1978-05-29 | 1979-12-10 | Sanyo Electric Co Ltd | Microwave oven |
-
1981
- 1981-07-13 CA CA000381617A patent/CA1169495A/en not_active Expired
- 1981-08-24 GB GB8125743A patent/GB2084436B/en not_active Expired
- 1981-09-16 JP JP14605081A patent/JPS5784588A/en active Pending
- 1981-09-24 DE DE19813138025 patent/DE3138025A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5784588A (en) | 1982-05-26 |
| GB2084436A (en) | 1982-04-07 |
| DE3138025A1 (en) | 1982-05-06 |
| GB2084436B (en) | 1984-09-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |