EP0849536A1

EP0849536A1 - Oven with high power radiant cooking elements and stored recipes and a method for automatically compensating for the current oven cavity temperature

Info

Publication number: EP0849536A1
Application number: EP97122324A
Authority: EP
Inventors: Scott J. Petty; Edward R. Cook; Nelson J. Ferragut
Original assignee: Raytheon Appliances Inc
Current assignee: Goodman Co LP
Priority date: 1996-12-18
Filing date: 1997-12-17
Publication date: 1998-06-24

Abstract

An oven with high power radiant cooking elements and stored recipes. Each stored recipe was developed at a particular oven cavity temperature which is stored with the recipe. If the recipe is recalled for use and the current oven cavity temperature is higher than the stored oven cavity temperature then the recipe will overcook or burn the food. Similarily, if the recipe is recalled for use and the current oven cavity temperture is lower than the stored oven cavity temperature then the recipe will undercook the food. The method automatically compensates for the difference between the stored oven cavity temperature and the current oven cavity temperature by proportionally adjusting the length of time of each stage of the stored recipe.

Description

FIELD OF THE INVENTION

The present invention relates to ovens having at least two high powered infrared radiant elements which are capable of operating at variable intensities or output power levels to cook food based upon a data base or recipe stored in memory. The recipe defines the intensity or output power level of each element for specific time periods during the cooking cycle and the temperature of the oven cavity when the recipe was developed. In particular, the present invention relates to a method of adjusting the length of the specific stages or time period during which each high power radiant element is at a specific intensity level to compensate for the difference between the oven cavity temperature when the recipe was developed and the oven cavity temperature when the recipe is going to be used.

BACKGROUND OF THE INVENTION

Ovens using high power radiant elements such as halogen tungsten lamps cook food quickly with infrared radiation. When cooking with infrared radiant elements the energy impinging upon the food surface is conducted into the interior of the food. Since the conduction of this infrared radiant energy varies substantially from food to food to properly cook many foods the output power level or intensity of the elements must he changed during the cooking process. The change in the output power levels of the elements allows the food time to conduct the infrared radiant energy into the interior of the food without burning the surface of the food. Accordingly, the user of the oven develops a unique data base or recipe for each food and stores this data base in memory. A recipe consists of a number of stages or segments each of which defines the output power level or intensity of each of the infrared radiant elements for a period of time. When the same food is going to be cooked the user of the oven retrieves the appropriate recipe from memory which is then used to control the oven during the cooking cycle.

The rate in which the food cooks is also affected by how hot the oven cavity is at the beginning of the cooking cycle. Basically a hot oven cooks faster than a cold oven. A problem occurs when the temperature within the oven cavity raises which can happen if the oven is used repeatedly without time between the cooking cycles for the oven to cool. If a particular recipe recalled from memory was developed when the oven was cool, with the elevated temperature of the oven cavity the recipe will result in overcooking and the possibility of burning the food. Conversely, a similar problem occurs if the retrieved recipe was developed with the oven cavity temperature high and the oven cavity temperature is now lower, the recalled recipe will result in undercooking.

Based upon the above, there exists a need to avoid cooking inconsistencies due to a difference in oven cavity temperature between when the recipe was developed and when the recipe is used. It is also desirable to avoid these cooking inconsistencies automatically when the recipe is recalled from memory for use.

SUMMARY OF THE INVENTION

The present invention provides consistency in cooking despite a difference between the oven cavity temperature when the recipe was developed and when the recipe is being used. The length of time of each stage of a stored recipe is adjusted up or down proportionally to the overall cooking time to compensate for the difference between the oven cavity temperature when the recipe was developed and the current oven cavity temperature. The temperature of the oven cavity when the recipe was developed is stored in memory as part of the recipe. After the recipe is retrieved from memory but before it is used, the current oven cavity temperature is measured. Now, the difference or delta between the original oven cavity temperature and the current oven cavity temperature is determined. A time adjustment factor is calculated by multiplying the original cooking time by the difference or delta and dividing by an empirically determined constant or number referred to as a Cook Factor. Finally, a ratio is calculated by adding the time adjustment factor to the original cooking time and dividing by the original cooking time. Now, the length of time for each stage or segment of the recipe retrieved from memory is multiplied by the ratio to achieve an adjusted time for each stage. The recipe with the adjusted time for each state is loaded into temporary memory and used to control the oven during the cooking cycle.

In this manner, the time period for each stage of the retrieved recipe is automatically and proportionally shortened if the current oven cavity temperature is higher than the oven cavity temperature when the recipe was developed. Conversely, the time period for each stage of the retrieved recipe is automatically and proportionally lengthened if the current oven cavity temperature is lower than the oven cavity temperature when the recipe was developed.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of an oven using high radiant infrared energy to cook food;

FIG. 2 is a cross section of the oven taken along line 1-1 of FIG. 1 showing the location of three high radiant infrared energy cooking elements and a temperature probe;

FIG. 3 is a front view of the control panel of the oven;

FIG. 4 is a front view of the switch bank of the oven;

FIGs. 5a - 5d are front views of the display screen of the oven showing different messages;

FIG. 6 is a block diagram of a control system for an oven using radiant energy elements;

FIGs. 7a and b are flow diagrams of the initialization of the power levels of the radiant cooking elements and timing for developing a recipe in real time;

FIG. 8 is a flow diagram of the changing of the power levels of the radiant cooking elements during the cooking cycle for developing a recipe;

FIGs. 9a and b are flow diagrams of continuing the cook time after a pause or extending the cook time and finally saving the developed and optimized recipe;

FIGs. 10 is a flow diagram of the optimization process for the developed recipe;

FIG. 11 is a flow diagram of the retrieval of a stored recipe from memory and of an automatic temperature compensation process according to the present invention;

FIG. 12 is a graph showing a portion of the calculation of the Cook Factor for the automatic temperature compensation process according to the present invention;

FIG. 13 is a graph showing a portion of the calculation of the Cook Factor for the automatic temperature compensation processing according to the present invention;

FIG. 14 is a graph showing a portion of the calculation of the Cook Factor for the automatic temperature compensation processing according to the present invention; and

FIG. 15 is a block diagram of a control system for an oven using radiant energy elements.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. On the contrary, the Applicant's intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

FIGs. 1 through 10 and 12-13 describe both a preferred and alternative methods, for developing a recipe in real time having a plurality of stages, optimizing the number of stages and storing the recipe into memory for subsequent use. However, any method of developing a recipe having a plurality of stages and storing the recipe in memory for subsequent use can be employed with the present invention provided an oven cavity temperature is stored as part of the recipe. FIG. 11 describes the retrieval of the recipe from memory and the automatic temperature compensation process of the present invention. This application is related to co-pending application titled "Oven with High Powered Radiant Cooking Elements and Methods of Developing, Optimizing, Storing and Retrieving Recipes for the Operation of the Oven", filed on the same date as the present application and assigned to the same assignee.

FIG. 1 illustrates a oven 10 that uses high power radiant cooking elements to cook food. The oven 10 has a housing 12 as is well known in the field. A windowed door 14 is capable of opening so that the user can place the food to be cooked within the oven cavity and view the cooking process through the window. A control panel 18 is mounted on the front wall 16 of the oven 10. The control panel 16 contains a plurality of buttons or switches and is more clearly illustrated in FIG. 3. A bank of numerically designated switches 20 is also mounted on the front wall 16 of the oven 10 and is more clearly illustrated in FIG. 4. The control panel 18 and the bank of switches 20 form the keypad that the user operates to convey information to the oven 10 or to initiate functions performed by the oven 10. A display screen 22 is mounted on the front wall 16 of the oven 10 to illustrate various messages or convey information to the user and is more clearly illustrated in FIGs. 5a-5d. The position of the control panel 18, the bank of switches 20 and the display screen 22 are matters of design choice.

FIG. 2 is a cross section of the oven 10 taken along line 1-1 to illustrate the position of the high power infrared radiant cooking elements. At least two such cooking elements are necessary to properly cook food in oven 10, however, any number of cooking elements above two can be used. In the preferred embodiment, three cooking elements are illustrated. The shape and position of the cooking elements is a matter of design choice. A first high power infrared radiant cooking element 30 such as a halogen tungsten lamp having a generally U-shape is placed towards the top of the oven 10. Cooking element 30 extends along both sides and the back of the oven 10. A second high power infrared radiant cooking element 32 having a generally linear shape is placed towards the top of the oven 10. Cooking element 32 extends from near the front wall 16 to the back of the oven 10 and is centrally located generally an equal distance from each side wall of oven 10. Finally, a third high power infrared radiant cooking element 34 having a generally U-shape is placed toward the bottom of the oven 10. Cooking element 34 extends along both sides and the back of the oven 10. As is well known, the food item to be cooked is placed on a shelf or rack (not illustrated for the sake of clarity) so that the top of the food item is exposed to infrared radiant energy from the top outside cooking element or the first cooking element 30 and the top center cooking element or the second cooking element 32 and the bottom of the food item is exposed to infrared radiant energy from the bottom cooking element or third cooking element 34. A temperature probe 35 is positioned along one of the side walls of the oven 10. The type of temperature probe and its location are matters of design choice. The temperature probe is used to determine the temperature of the oven cavity before a cooking cycle begins for the automatic temperature compensation process.

FIG. 3 illustrates the control panel 18 shown generally in FIG. 1. The control panel comprises a power on key or switch 36, a time entry key 38, a 100% intensity key 40, menu key 42, add key 44 which adds an additional 20 seconds to the overall cooking cycle, save key 48, enter key 50, delete key 52, left arrow key 54 and right arrow key 56. FIG. 4 illustrates the bank of switches 20 shown generally in FIG. 1. The bank of switches 20 comprises a plurality of numeric keys 60 ranging from 0 through 9, stop/reset key 62 and start key 64. The layout or position of the various keys of the control panel 18 and the bank of switches 20 is a matter of design choice. In addition the type of switch or key is also a matter of design choice and is well within the ability of someone skilled in the art. The function performed in response to a particular key being activated is described in the flow charts of FIGs. 7 through 11.

FIG. 5a through 5d are illustrations of the display screen 22 shown generally in FIG. 1. The various messages and information appearing on the display screen is described in the flow charts of FIGs. 7 through 11. FIGs. 5a-5d show a sample of the various messages displayed on the screen 22, for the sake of clarity other message are described in the specification but not illustrated in the drawing since the specific text of any message is a matter of design choice. Any type of display screen can be used as is well known to one skilled in the field.

The infrared

radiant cooking elements

30, 32 and 34 generate energy that impinges upon the food surface and is then conducted into the interior of the food for proper cooking. However, the conduction of the infrared radiant energy varies from food to food and many foods require the output power or intensity level of the cooking elements to vary during the cooking process in order to assure that the food is properly cooked throughout without burning the surface of the food. Accordingly, the user of the oven 10 must develop a recipe or data base, for each food item to be cooked. The recipe or data base consists of a number of stages or segments each of which defines the output power level or intensity of each infrared radiant element for a period of time. The user of the oven 10 develops the recipe by initially selecting and storing in temporary memory the output power level or intensity of each cooking element with the run time equal to zero. This data forms the first stage of the recipe. At this time the user also stores in temporary memory the overall cooking time. The user presses the start button to initiate the cooking cycle and views the food as it is being cooked and, as needed, changes the power output level or intensity level of the cooking elements. During the cooking cycle each time the intensity of a cooking element is changed a new stage in the recipe is formed and the intensity of each cooking element and the run time at which the change was made are stored in the temporary memory. When the total original cooking time expires or the power to the radiant element is shut off the user is given the opportunity to continue with the original cook time or increase the overall cooking time. If the user continues with the original cook time or increases the overall cooking time the above process of creating stages by changing the intensity of the cooking elements and storing data in temporary memory is repeated. If the user does not continue with the original cook time or increase the overall cooking time but rather chooses to save the recipe, then the final stage is completed and the intensity of each cooking element is set to zero and the run time are stored in temporary memory. Now, the developed recipe is optimized by compressing together consecutive stages if the run time of a stage is below a predetermined limit as is more fully explained by reference to the optimization process set forth in FIGs. 10a and b. The optimized recipe is then stored in permanent memory and can be retrieved for controlling the oven 10 when the same food item is to be cooked in the future. The present invention allows the user extensive flexibility to develop a recipe by changing the output power level or intensity of the cooking elements during the actual cooking process based upon the user's visual observation of the food. In the preferred embodiment, even a recipe recalled from permanent memory can be modified by the user during the subsequent cooking process and the modified recipe stored in memory.

As shown in FIG. 6, the user of the oven 10 supplies information or operating instructions from an input control or keypad 70 comprising the control panel 18 and the bank of switches 20 to a microprocessor 72. Various calculations and functions are implemented by the microprocessor 72 which also provides an output to the display 22 and to the

radiant energy elements

30, 32 and 34. The calculations and functions performed by the microprocessor 72 are described in detail with reference to the flow charts of FIGs. 7 through 11. Any microprocessor capable of performing the various calculations and implementing the various instructions can be used, in the preferred embodiment Hatchi microprocessor H8/338 is used.

The preferred method or process of original recipe development is illustrated by the flow chart of FIGs. 7a and b. At step 100 the user turns on the overall power to the oven 10 by depressing the power key 36 on the control panel 18. The display screen 22 shows that the oven is ready at step 102 for either original recipe development or the selection of already stored recipes in menu A, refer to FIG. 5a. Now at step 104 the keypad comprising the control panel 18 and the bank of switches 20 is scanned to detect user input. If the user selects a recipe previously stored in memory at step 106 by pressing a number key 60 which identifies the stored recipe as latter explained, then the process continues as explained with reference to FIG. 11. If a stored recipe is not selected the user is going to develop a new recipe and the time entry key 38 is depressed and detected at step 108. If the time entry key 38 is not pressed then the process continues to scan the keypad for user inputs at step 104. If the time entry key 38 is pressed a temporary memory, typically a random access memory (RAM) which saves user inputs is cleared at step 110. Next, at step 112 all of the high power radiant cooking elements are set for operation at 100% intensity or power level and the total cook time is set to zero. Of course, the intensity levels of the elements and the total cook time could be set to any value. Next, at step 114 the intensity level for each cooking element and the total cook time are shown on the display 22 as illustrated in FIG. 5b. The letter C refers to the top center radiant element, 32, the letter O refers to the top outside radiant element 30 and the letter B refers to the bottom radiant element 34. A cursor is flashing under the letter C to indicate that if the user changes intensity or power level as explained below that the cooking element changed will be the top center element 32. The cursor is moved by depressing the right and left

arrow keys

54 and 56 on control panel 18.

Now the keypad is scanned for user inputs at step 116. Next at step 118 it is determined whether or not one of the keys 60 from switch bank 20 is depressed. If a number key 60 is not pressed the process continues to scan the keypad for user inputs at step 116. However, if a number key 60 is pressed the process moves to step 120 to determine whether or not a cooking element is selected. A cooking element is selected if the cursor is placed under the letter designation C, O or B. Of course, the cursor is moved to the left or right by depressing

arrow keys

54 or 56 respectively. Typically the cursor is moved to the cooking element whose intensity level is to be changed before the number key 60 is pressed. The intensity level or output power level of the cooking element selected is changed from the originally selected 100% to whatever percentage is represented by the depressed number key 60. For example, if the user depresses the number 6 key 60 and the cursor is flashing under letter C, then the output power level of the center cooking element 32 is changed from 100% to 60%. The new intensity level is stored in the temporary memory (RAM) at step 122. Now, at step 124, the new intensity level is displayed on screen 22 as shown in FIG. 5c. The process now returns to step 116 and continues to scan the keypad for user inputs. The above process is repeated as needed to set the intensity level of each of the

cooking elements

30, 32 and 34. For example, the user can move the cursor under the letter O by depressing the arrow key 54 and can then change the intensity of the outer cooking element 30 to 70% by depressing the number 7 key 60. The new intensity level for cooking element 30 is stored in temporary memory and displayed on screen 22. Now the user can move the cursor under the letter B by depressing the arrow key 54 and can then change the intensity of the bottom cooking element 34 to 50% by depressing the number 5 key 60. The new intensity level for the bottom cooking element 34 is stored in temporary memory and displayed on screen 22. The screen 22 now shows the intensity level of the center element 32 or C as 60%, the outer element 30 or O as 70% and the bottom element 34 or B as 50%. Of course, if the user desires to have one or more of the cooking elements at 100% intensity the user simply moves the cursor past that cooking element designation on the screen 22. If a cooking element is not selected at step 120 then the process determines if the cooking time is selected at step 126. The cooking time is selected by moving the cursor to be under the time indication. Again, the user moves the cursor to indicate cooking time before entering the desired total cooking time by depressing the appropriate keys 60. The new cooking time selected, for example, two minutes and thirty-three seconds, is stored in RAM at step 128 and shown in display 22 at step 130. At this point the initial power level or intensity of each

cooking element

30, 32 and 34 and the original cook time are stored in temporary memory and illustrated on the display 22 as shown in FIG. 5d.

The process continues to scan the keypad for user input at step 116. If the stop/reset key 62 is pressed at step 132, then the RAM memory is cleared at step 134 and control of the process is returned to step 102 to display the "Ready" message on screen 22. If the stop/reset key 62 is not pressed, then at step 136 the process checks to determined whether or not the start key 64 is pressed. If the start key 64 is not depressed the process continues to scan the keypad for user input at step 116. If the start key 64 is pressed, then at step 138 it is determined whether or not the user has entered an appropriate cooking time. If the total cook time is not greater than zero, then the user did not enter the cook time and then at step 140 the message "enter time" is shown on the display 22 and control of the system is returned to step 116 for entry of the cook time. If a cook time has been entered, then the process moves to step 142 to determine whether the oven door is closed. If the door is not closed then at step 144 the message "shut door" is shown on the display and the process returns to step 116. If the oven door is closed, the process moves to step 146 where the cooking stage number is set to stage number 1 and the run time is set to zero. Each stage of the cooking cycle has a specific run time which indicates the beginning point of the stage, accordingly stage 1 has a run time equal to zero. It would also be possible to have each stage have a separate run time equal to the time period of that stage and, of course, subsequent changes to the process would be necessary to accommodate this change as would be well known to one of ordinary skill in the field. Now at step 148 the oven cavity temperature is measured temperature by probe 35 and stored in RAM for future use as is explained with reference to FIG. 11. Next at step 150 the stage number and the run time is stored in temporary memory or RAM. Finally at step 152 all cooking elements are turned on to the power levels specified. Now the run clock is started at step 154 to determine the total time of the stage and at step 156 the cooking time clock begins counting down the total cooking time.

Now the oven is operating and the user is able to view the food being cooked. The process is scanning the keypad for user inputs at step 158. If the user desires to change the power level of one of the cooking elements, the cursor is moved under the designation for the cooking element that is to be changed and the appropriate numeric key 60 is pressed. For example, if cooking element 30 is to be changed, the cursor is moved under the letter O on the display 22 by depressing the

appropriate arrow keys

54 or 56 and if the current intensity level of 70% is to be changed to 60% intensity level, the number 6 key 60 is pressed. If the intensity level of the selected element is to be raised to 100% intensity, then 100% intensity key 40 on control 18 is depressed. Now, the process detects whether a number key 60 is depressed at step 160. If a number key is not pressed the process through a series of intermediate steps continues to scan the keypad at step 158. If a number key 60 is pressed, then at step 162, the process determines which one of the cooking elements is selected and if the new power level of the selected cooking element is different than the current power level. If the new power level is the same as the current power level the process through a series of intermediate steps continues to scan the keypad at step 158. If the new power level of the selected cooking element is different than the current power level then the stage number is incremented by one at step 166. A new stage is now in operation and at step 168 the number of stages is compared against a maximum limit of 25. Any numerical limit can be placed on the number of stages to allow flexibility and creativity to the user. If the stage number is not greater than the limit then at step 170 the run time for the new stage or the time at which the change was made, the new stage number and the intensity levels of the cooking elements are stored in temporary memory (RAM). For example, if the change in intensity level of cooking element 30 or O changed from 70% to 60% after 10 seconds of operation the process would store in temporary memory stage 2, run time equal 10, and intensity levels C equals 60%, O equals 60%, B equals 50%. If the stage number is greater than the limit at step 168 then at step 171 the new intensity levels and run time for stage 26 or greater are substituted for the intensity levels and run time for stage 25 stored in temporary memory. Next the selected cooking element is changed to the new power level at step 172 and the power levels of the cooking elements are displayed at step 174.

Now, at step 176 the stop/reset key 62 is checked, if the stop/reset key 62 is depressed, the power to the cooking elements is shut off and the run time and cook time are stopped at step 178 and the message "paused" is displayed at step 180. If the stop/reset key 62 is not depressed at step 176, then the condition of the door is checked at step 182. If the door is open the process moves to step 178 to shut off power to the cooking elements and stop the run time and cook time and the message "paused" is displayed at step 180. If the door is not open at step 182, then the cooking time is checked at step 184. If the cooking time is equal to zero then the process proceeds to step 178 and shuts off power to the cooking elements and the message "paused" is displayed at step 180. If the cooking time is not equal to zero then the process continues to scan the keypad for user inputs at step 158. The entire sequence is now repeated which enables the user to again modify the power level of one of the cooking elements to create another stage in the development of a recipe.

After step 180, the cooking time is checked at step 186 and if the cook time does not equal zero, which means that the power was shut off because the step/reset key 62 was pressed at step 176 or it was determined that the door was open at step 178, in either event the message "press start to continue or save to create a recipe from cooking cycles" is shown at display 22 at step 188. If the user wants to continue the start key 62 is pressed. If the user wants to save the developed recipe then the save key 48 is depressed. Both of these options are described below. The process at step 190 scans the keypad for user inputs. Next, at step 192 it is determined whether or not a number key 60 is pressed. If a number key 60 is not pressed then the process goes to step 194 to determine if the stop/reset key 62 is pressed. If the stop/reset key 62 is not pressed then the process advances to step 196 to determine if the start key 62 is pressed. If the stop/reset key 62 is pressed then the process advances to step 198 and the RAM memory is cleared and the process returns to step 102 and displays the "ready" message.

If the start key 62 at step 196 is pressed then the process determines whether the cook time is greater than zero at step 200. If the cook time is not greater than zero, then the process displays "enter time" at step 202 and returns to step 190 to scan the keypad for user inputs. If the cook time is greater than zero, then the process goes to step 204 to determine whether or not the door is open. If the door is open then at step 206 the message "shut door" is displayed and the process returns to step 190 to scan the keypad for user input. If the door is not open at step 204, then the process returns to step 152 to turn on the cooking elements to the power level specified.

If the start key 62 is not pressed at step 196 then the process advances to step 208 to determine whether or not the save key 48 is pressed. If the save key 48 is not pressed the process returns to step 190 to scan the keypad for user input. Now, if the cook time at step 186 is equal to zero, then the original time set by the user has expired. The process now displays the message "Enter time to Continue or Press Save to Create Recipe for Cook Cycle" at step 210 and the process scans the keypad for user input at step 190.

If a number key 60 is pressed at step 192, the process determines if the pause at step 180 was initiated by the cooking time being equal to zero at step 212. If the pause was not initiated by the cooking time being equal to zero then the process checks if the stop/reset key 62 is pressed at step 194 and continues as described above. If the pause was initiated by the cooking time being equal to zero then at step 214 the cooking time is increased by the amount entered by depressing the number key 60 and the new cook time is stored in temporary memory. Of course, to continue with the expanded cook time, the user depressed the start key 64 which is detected at step 196.

If the save key 48 is pressed at step 208 then all cooking element power levels are set to zero and the cooking time is reset to zero at step 216. Next at step 218 the stage number is incremented and at step 220 the new stage number is compared to the predetermined limit. If the last stage number is less than the predetermined limit then at step 222 the last stage number, the run time and the cooking element power levels of zero are stored in the temporary memory. If the last stage number is greater than the limit, then at step 224 the cooking element power levels and run time of stage 25 replace with the last stage data in the temporary memory. Now, the process advances to the optimization process at step 226.

At step 226 the message "To Save Recipe Select Recipe #A_" is displayed on screen 22 if the A menu is active. Of course, if the B or C menu is active the message refers to that active menu. The keypad is now scanned for user input at step 228. If the user desires to select a different menu the menu key 42 is pressed. This is detected at step 230. The present menu selected is detected at step 232. If the present menu is A, then at step 234 the menu B is selected. If the present menu is B, then at step 236 the menu C is selected. If the present menu is A, then at step 238 menu A is selected. By following the above sequence the user selects the menu in which the developed recipe will be stored.

Now at step 240, the process checks to determine if a number key is pressed. If the user hasn't depressed a number key 60 the process checks to determine if the reset key 62 is pressed at step 242. If the user presses the reset key 62, the save process ends at step 244 and the process returns to step 102 to display a Ready message. If the reset key is not pressed, the process continues to scan the keypad for user input. If a number key 60 is pressed, the recipe number is made equal to the number key 60 pressed at step 246. The process now displays a message such as "enable/disable auto temp feature" on screen 22 at step 248. The cursor initially is positioned under the word "enable" and to select enabling of the automatic temperature compensation feature the user depresses enter key 44. If the user desires to disable this feature the right arrow key 54 is pressed moving the cursor under the word "disable". Now, the user presses enter key 50. Now, at step 250, a message such as "saving recipe: B5" is displayed on screen 22. Of course, the message displayed on screen 22 will reflect the menu and key pressed by the user. The process now goes to the optimization process at step 252. Finally, the optimized recipe and the status of the automatic temperature compensation feature is stored in permanent memory designated by the menu and key 60 selected at step 254.

An example of a developed recipe store in temporary memory is set forth in Table 1 below.

TEMPORARY MEMORY
		POWER LEVELS
STAGE NO.	RUN TIME	C	O	B
1	0	60	70	50
2	10	60	60	50
3	12	60	60	40
4	45	60	60	0
5	68	60	60	100
6	72	60	20	100
7	80	20	20	100
8	120	30	20	100
9	125	100	100	100
10	148	100	100	30
11	153	0	0	0

The optimization process shown on FIGs. 10a and 10b reduces the number of stages developed by the user to six stages by eliminating stages that have a very short run time. Of course, the number of stages selected for the optimized recipe is a matter of design choice. The basic premise of the optimization process is to eliminate stages during which the changes to the intensity level of the cooking elements will have no practical impact on the food being cooked because the run time is so short and to reduce the amount of permanent memory needed to store a recipe. Very short run times can occur if the user desires to change the intensity level of two of the cooking elements. Following the process described above and referring to Table 1 of a typical temporary memory at stage 2 the user has changed the intensity level of the outside cooking element 30 or O from 70% to 60% at run time equal to 10 seconds. Now, promptly after making the change resulting in stage 2 the user changes the intensity level of the bottom cooking element 34 from 50% to 40% at run time equal to 12 seconds. This is basically as fast as the user can operate the keypad to change intensity levels. Now, if stage 2 were eliminated the only difference would be that the intensity level of cooking element 34 or B remains at 50% for two additional seconds before being changed to 40%. Thus, the elimination of stage 2 will have practically no affect on the food being cooked.

The optimization process is described with reference to the flow diagram of FIGs. 10a and 10b. At step 300 the minimum stage duration or "filter" is set to five seconds. The user has no control over this predetermined time period as it is selected by the manufacturer. The stage duration or filter time is a matter of design choice. Next at step 302 the "Last Stage" parameter is set equal to the last stage entered into the temporary memory during the cooking cycle. Using the cooking cycle from the above Table "Last Stage" = 11. Now, at step 304 the number of "Stages to Delete" is set to 0. At step 306, a transition memory is cleared. The transition memory is typically a random access memory (RAM) and it stores each stage of the optimized recipe during the optimization process before the optimized recipe is loaded into the permanent memory (ROM). At step 308, the Last Stage is compared to the maximum number of stages. In the example, the Last Stage or 11 is compared to the preselected maximum number of stages or 6. If the number of stages in the developed recipe were less than the maximum number of stages allowed then the process loads the stages stored in the temporary memory into the transition memory at step 310. Now, at step 312, the stages stored in the transition memory are loaded into permanent memory and the optimization process ends at step 314.

If the number of stages in the developed recipe is greater than the maximum number of stages allowed, optimization is necessary. At step 316 the "Stages to Delete" is set equal to the Last Stage minus the maximum number of stages allowed. In the example, Stages to Delete = 11 - 6. Now, at step 318, the Stages Deleted is set equal to 0. Next, at step 320, it is determined if the number of Stages Deleted is less than the number of Stages to Delete. Since in the example, Stages Deleted (0) is less than Stages to Delete (5) the process moves to step 322, where the minimum stage duration allowed or filter time is increased by one second and the Stages Deleted is set to zero. The filter time is increased at this point even though the original filter time has not been used in the optimization process. Now, at step 324, the Stage No. N is set equal to 2. The first stage to be processed through the optimization sequence is the second stage stored in the temporary memory. Next, at step 326, the Stage N is compared to the last stage. In the example, N = 2 and Last Stage = 11 and since 2 is less than 11 the process moves to step 328.

Now, the run time of the developed recipe stored in temporary memory at Stage N minus the filter time is compared to the run time of the developed recipe at stage N - 1. In the example, the run time for the developed recipe in temporary memory at stage 2 is 10 seconds and the filter time is 6 seconds and the run time for the developed recipe in temporary memory at stage 1 is 0 seconds, so that 10 - 6 or 4 is not less than or equal to 0. Accordingly, the process moves to step 330 and N is incremented. The process now returns to step 326 to determine if N is less than the last stage. N is now equal to 3 and the Last Stage is still 11. Accordingly, the process again proceeds to step 328. During this cycle the run time for the developed recipe in temporary memory at stage 3 minus the filter time is compared to the run time of developed recipe in temporary memory at stage 2. The run time for stage 3 is twelve seconds so 12 - 6 = 6 and the run time for stage 2 is 10 seconds. Since 6 is less than or equal to 10, the process moves to step 332 where the stages deleted is incremented. The process increments N at step 330 and returns to step 326 to begin another sequence. If the above process is followed for the sample developed recipe in the Table the stages deleted equals 4 through N= 10, N = 11 and at step 326 since N is not less than the Last Stage and the process moves to step 330. Since the stages deleted (4) is still less than the stages to delete (5), the process moves to step 322 to repeat the above process with the filter time increased by 1 so that filter time = 7 seconds and stages deleted reset to 0. After this sequence is completed, stages deleted = 5.

The process now at step 320, determines that stages deleted is not less than Stages to Delete and proceeds to step 334. Now, Stage No. X is set equal to 1 and Stage No. Y is set equal to 2. Next, at step 336, Y is compared to the last stage number stored in temporary memory. If Y is not greater, then the process moves to step 338. Now, the run time of the developed recipe stored in temporary memory at Stage Y - 1 is compared to the run time for the developed recipe stored in temporary memory at Stage Y minus the filter time. In the present example, Y = 2 and Filter time = 7 seconds and the run time of stage 1 = 0 and the run time of stage 2 = 10. Since the run time for Stage Y - 1 (0) is less than the run time for Stage Y (10) minus filter time (7) the process proceeds to step 340. The stage (Y - 1) stored in temporary memory is now loaded into the transition memory at Stage X. In the example, stage 1 in the temporary memory is stored as stage 1 in the transition memory. Now at step 342 X is incremented and at step 344 Y is incremented and the process returns to step 336. Y now equal to 3 is still not greater than the Last Stage (11) so the process goes to step 338.

The run time for the developed recipe at Stage Y - 1 is compared to the run time for the developed recipe at Stage Y minus the filter time. The run time for stage 2 is 10 seconds, the run time for Stage 3 is 12 seconds and the filter time is 7 seconds. Accordingly, 10 is not less than 12 - 7 and the process moves to step 344 to increment Y. The data stored in temporary memory for the developed recipe at stage 2 is not loaded into the transition memory since the run time between stage 2 and stage 3 is too small.

The process now returns to step 336 with Y = 4 and X = 2. Since Y is still not greater than the Last Stage (11) at step 338 the run time for the developed recipe in temporary memory at stage 3 is compared to the run time for the developed recipe in temporary memory at stage 4 minus the filter time. Accordingly, 12 is less that 45 - 7 and at step 340 the data in the temporary memory for stage 3 is loaded into the transition memory at stage 2. Now, X is incremented to 3 at step 342 and Y is incremented to 5 at step 344. The process again returns to step 336 to repeat until Y is incremented to 12. Now Y is greater than the Last Stage in temporary memory at step 336 and the process moves to step 346. Now, the data in the Last Stage of the temporary memory is loaded into the transition memory at stage X = 6. Now the process proceeds to step 312 and the data in the transition memory is loaded into the permanent memory and the optimization process ends at step 314.

During the above optimization process the data for the developed recipe stored in temporary memory at

stages

2, 5, 6, 8 an 10 has not been transferred to the transition memory. The transition memory has the following six stages:

TRANSITION MEMORY
		POWER LEVELS
STAGE NO.	RUN TIME	C	O	B
1	0	60	70	50
2	12	60	60	40
3	45	60	60	0
4	80	20	20	100
5	125	100	100	100
6	153	0	0	0

The data stored in the transition memory or RAM is stored in permanent memory or ROM. The process of developing a recipe in real time, optimizing the recipe and storing the recipe in permanent memory is now complete.

The user can select a recipe stored in permanent memory at step 106 by depressing a number key 60. If a number key is not pressed scanning the keypad continues at step 104. If a number key 60 is pressed by the user, then at step 250 in FIG. 11 the process checks the permanent memory to determine if a recipe is stored in that location. As described above, the user can select other menus by depressing the menu key 42. If the permanent memory location does not contain a recipe the process returns to step 102 to display the ready message. Of course, in addition to developed recipes stored in permanent memory the manufacturer can store standard recipes in permanent memory. A standard recipe is for a common food item to be cooked and is developed by the manufacturer. These standard recipes can be selected by the user in the same fashion that developed recipes are selected. If a recipe is stored in the permanent memory location, the process at step 252 checks to determine if the automatic temperature compensation feature is enabled.

The automatic temperature compensation feature is used to adjust the recipe depending upon the difference between the oven cavity temperature stored with the recipe and the current oven cavity temperature. In the preferred embodiment, the oven cavity temperature stored with the recipe is the temperature of the oven cavity when the recipe was developed. However, other temperatures could be stored with the recipe, for example, if the retrieved recipe is a standard recipe loaded into permanent memory by the manufacturer the stored temperature may be ambient or 74°. Furthermore, determining the oven cavity temperature when the recipe is being developed as explained above and then adding or subtracting some number of degrees for example 10° is considered within the spirit and scope of the present invention. If the current oven cavity temperature is higher than the temperature when the recipe was developed, the retrieved recipe without compensation may burn the food. In a similar vain, if the oven cavity temperature when the recipe was developed was greater than the current temperature, the retrieved recipe without compensation may leave the food undercooked. The automatic temperature compensation feature automatically adjusts the run time of each stage of the stored recipe to take into effect the temperature of the oven cavity.

If the automatic temperature compensation is not enabled for the recipe selected then at step 254 the selected recipe from permanent memory is loaded into temporary memory and as is well known by those of ordinary skill in the art the cooking routine is begun at step 256. If the automatic temperature compensation feature is enabled then the present oven cavity temperature is measured at step 258. Now, at step 260 the original oven cavity temperature and cook time stored in permanent memory is loaded into temporary memory. The difference between the original oven cavity temperature and the present oven cavity temperature is calculated as Delta in step 262. For example, if the original temperature was 80°F and the current temperature is 195°F perhaps due to prior operation of the oven, then Delta = 80°F - 190°F = -115°F. Now, the cook time adjustment factor is calculated at step 264 to be Delta times the original overall cooking time divided by the Cook Factor. For example, the original cook time was 153 seconds and the Cook Factor is 748. Accordingly, time adjustment factor = (-115 x 153)/748 = - 23. Since the process does not require a high degree of accuracy the time adjustment factor is rounded to the nearest integer. Now, at step 266, the Ratio is calculated as the original cooking time plus the time adjustment factor divided by the original cooking time. For example, in this situation, Ratio = 153 + (-23)/153 = 0.84. At step 268, the stage data from the selected recipe is loaded into temporary memory. Now, at step 270 the Ratio is multiplied times the run time of each stage of the selected recipe and at step 254 loaded into temporary memory. Now, the cooking routine starts at step 256. The automatic temperature compensation process applied to the example of a developed recipe discussed above would result in the automatically temperature compensated recipe stored in temporary memory as shown in Table 3.

AUTOMATIC TEMPERATURE COMPENSATED RECIPE
		POWER LEVELS
STAGE NO.	RUN TIME	C	O	B
1	0	60	70	50
2	10	60	60	40
3	38	60	60	0
4	67	20	20	100
5	105	100	100	100
6	128	0	0	0

The Cook Factor is an empirically derived number and may vary depending upon the thermal characteristics of the oven. In order to determine the Cook Factor a recipe developed with an oven cavity temperature of ambient or 74°C and an overall cooking time of 210 seconds is cooked with an oven temperature in the mid range, for example, 163°F and the amount of time that the overall cooking time must be reduced in order to obtain a properly cooked food product is noted on a graph as shown in FIG. 12. For example, the overall cooking time must be reduced by 19 seconds. The ordinant or y-axis is measured in seconds that the cook time adjustment factor is changed and the abscissa or x-axis is the oven cavity starting temperature in degrees Fahrenheit (°F). Now, the same recipe is used with the oven cavity temperature in the high range for example 252°F and the amount of time that the overall cooking time must be reduced in order to obtain a properly cooked food product is noted on the graph as shown in Figure 12. For example, the overall cooking time must be reduced by 49 seconds. Any recipe can be used for this process and a minimum of three test points must be used as shown in FIG. 12. However, more test points can be used. Since the amount of time that the overall cook time must be reduced to get a properly cooked food is a subjective determination made by the operator, the more test points used the more accurate the result. Since the three test points do not lie on a straight line a best linear fit calculation is applied to obtain the solid time shown in FIG. 12.

Now, another recipe with an oven cavity temperature in the midrange, for example 163°F and an overall cooking time of 225 seconds is cooked with the oven cavity temperature of ambient or 74°F and the amount of time that the overall cooking time must be increased in order to obtain a properly cooked food product is noted on a graph as shown in Fig. 13. For example, the overall cooking time must be increased by 37 seconds. Now, the same recipe is used with the oven cavity temperature in the high range, for example 252°F and the amount of time that the overall cooking time must be reduced in order to obtain a properly cooked food product is noted on the graph as shown in Fig. 13. For example, the overall cooking time must be reduced by 35 seconds. Again, since the three test points do not lie on a straight line a best linear fit calculation is applied to obtain the solid line shown in FIG. 13.

Now, another recipe with an oven cavity temperature in the high range, for example 252°F and an overall cooking time of 170 seconds is cooked with an oven cavity temperature of ambient or 74°F and the amount of time that the overall cooking time must be increased in order to obtain a properly cooked food product is noted on a graph as shown in FIG. 14. For example, the overall cooking time must be increased by 32 seconds. The same recipe is used with the oven cavity temperature in the mid range, for example 163°F and the amount of time that the overall cooking time must be increased to get a properly cooked food product is noted on the graph as shown in FIG. 14. For example, the overall cooking time must be increased by 20 seconds. Again, since the three test points do not lie on a straight line a best linear fit calculation is applied to obtain the solid line as shown in FIG. 14.

While three sample recipes with different oven cavity temperatures are described in the above examples, more sample recipes can be used which would increase the accuracy of the process. Furthermore, the performance of the best linear fit calculation to obtain the solid lines in FIG. 12, 13 and 14 is within the ability of one of ordinary skill in the field.

Using the best linear fit line in each graph, the cooking time adjustment for each recipe is determined. Table 4 shows the oven cavity temperature for each recipe, the cooking time adjustment determined by test, the cooking time adjustment based upon the best linear fit line and average cooking time adjustment as explained below.

COOK FACTOR CALCULATION
OVEN CAVITY TEMP °F	COOKING TIME ADJUSTMENT (SEC.)
	TESTED	BEST FIT	AVE.
74	0	0	0
163	-19	-23	-25
252	-49	-46	-50
74	37	33	27
163	0	0	0
252	-35	-34	-27
74	32	37	40
163	20	18	20
252	0	0	0

Now, using the best linear fit cooking time adjustment, the Cook Factor for each of the above six non-zero examples is calculated as Cook Factor equals the Original Oven Cavity Temperature minus Oven Cavity Temperature times the Original Overall Cooking Time divided by the best linear fit time adjustment factor. The average Cook Factor for all six examples is 745. Now, the average cooking time adjustment factor is calculated for each example using the average Cook Factor of 745. The average cooking time adjustment factor for each example is rounded to the nearest integer, refer to Table 4. The average cooking time adjustment factors are shown by the dotted line in each of the graphs in FIGs. 12, 13 and 14. Now, using the average cooking time adjustment factor rounded to the nearest integer, the Cook Factor for each of the six samples is determined and then the average Cook Factor is determined, in this example the average Cook Factor using the average cooking time adjustment factor rounded to the nearest integer is 748.

FIG. 15 is a block schematic diagram of the overall oven control as described by the flow diagrams of FIGs. 7 through 11. The user operates the input control 350 comprising the control panel 18 and the bank of switches 20. The input control 350 sends a signal to the intensity control 352 for the radiant

energy cooking elements

30, 32 and 34. The intensity control comprises solid state switching devices such as trices and would be well known to one of ordinary skill in the field and is connected directly to the radiant

energy cooking elements

30, 32 and 34. The input control 350 also sends a signal to the clock means 354 to set the overall cook time and run time. The intensity level of each cooking element at time equal to zero is stored in RAM memory 356 for temporary storage. The overall cook time, run time and oven cavity temperature are also stored in RAM memory 356. The intensity level of each cooking element and the overall cook time is shown in display 22. During the cook cycle the user can change the intensity level one of the cooking elements, the new intensity level and the time the change was made are stored in RAM memory as another stage in the recipe. The user can make additional changes to the intensity level of one of the cooking elements until the cook time elapses or the power to the cook elements is shut off The stages of the recipe stored in RAM memory are now transferred to ROM memory 358. The user through the input control can retrieve a stored recipe from ROM memory 358 to control the oven 10.

It will be understood that various changes in the details, arrangements and configurations of the parts and assemblies which have been described and illustrated above in order to explain the nature of the present invention may be made by those of ordinary skill in the art within the principle and scope of the present invention as expressed in the appended claims. It is not intended to limit the invention to the precise forms disclosed above and many modifications and variations are possible in light of the above teachings. A program listing for the method of automatically compensating for the difference between the stored oven cavity temperature and the current oven cavity temperature, for the operation of an oven having high power radiant cooking elements in accord with the present invention follows:

Claims

A method of modifying a stored recipe for use in controlling an oven having radiant elements to cook food, said recipe having a plurality of stages the temperature of the oven cavity at the time the recipe was developed, and the overall cook time, each stage having a time period comprising the steps of:

measuring the present oven cavity temperature;

determining the difference between the oven cavity temperature at the time the recipe was developed and the current oven cavity temperature;

determining a time adjustment by multiplying the overall cook time by said difference and dividing by a cook factor cook time;

determining a ratio by adding the time adjustment to the overall cook time and dividing by the overall cook time;

multiplying the duration of each stage of the recipe by said ratio to arrive at a modified stage;

storing said modified stages in temporary memory;

controlling the cooking cycle of said oven by said modified stages.
A method of cooking food in an oven using radiant energy cooking elements and having a stored recipe including an oven cavity temperature and a plurality of stages retrieving said recipe from memory;

determining the current oven cavity temperature;

determining a differential relationship between the stored oven cavity temperature and the current oven cavity temperature;

proportionally modifying the length of each stage based upon the differential relationship between the stored oven cavity temperature and the current oven cavity temperature.
A method of cooking food in an oven using radiant energy cooking elements as set forth in claim 2 wherein said step of determining a differential relationship comprises:

determining the difference between said stored oven cavity temperature and said current oven cavity temperature;

determining a time adjustment by multiplying the overall cooking time by said difference and dividing by a cook factor; and

determining a ratio by adding said time adjustment to the overall cooking time and dividing by the overall cook time.
A method of cooking a food in oven using radiant energy cooking elements as set forth in claim 2 wherein said stored oven cavity temperature is the oven cavity temperature at the time the recipe was developed.
A method of cooking a food in an oven using radiant energy cooking elements as set forth in claim 2 wherein said stored oven cavity temperature is ambient temperature.
An oven having at least two radiant energy elements for cooking food and a memory storing at least one recipe comprising a plurality of stages and an oven cavity temperature;

means for measuring the current oven cavity temperature;

means for retrieving a recipe from memory;

means for adjusting the duration of each stage of the retrieved recipe based upon the relationship between the stored oven cavity temperature and the current oven cavity temperature.