GB2323685A

GB2323685A - Control of a microwave oven by sensing temperature or gas level and food weight

Info

Publication number: GB2323685A
Application number: GB9806315A
Authority: GB
Inventors: Ghong-Mo Chung; Hyung-Jun An; Mi-Yim Kim
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 1997-03-24
Filing date: 1998-03-24
Publication date: 1998-09-30
Also published as: GB9806315D0; JPH10300095A; JP2916464B2

Abstract

A method of operating a microwave oven uses one or more sensors to monitor the progress of cooking. The sensor may sense the temperature in the cooking chamber S40, or may sense the level of gas emitted from the food. A reference temperature or gas level value is set, and the sensor monitors when the temperature or gas level in the cooking chamber reaches the predetermined reference level S50. Once this occurs, time counting starts S60, and a residual cooking time is defined, which can be a predetermined time or can be calculated from the time elapsed thus far. The food is then further cooked for the residual time, and only when this residual time has elapsed is cooking terminated S70, S80. This prevents undercooking or overcooking. In further embodiments (figures 6 and 8), the foodstuff can be weighed in the oven, and a reference time calculated from this measurement. A maximum and a minimum reference time can also be calculated.

Description

Control of a Microwave Oven Description The present invention relates to a microwave oven and a method of controlling cooking by a microwave oven.

A known microwave oven uses a weight sensor to control the cooking process. A cooking mode is selected using a key input unit and initiated. The mode might be, for example, an automatic defrosting program. The key input unit sends a corresponding key signal to a controller 15, while a weight sensor 8 weighs the foodstuff 1 and sends a food weight value to the controller 15. The controller 15 then calculates a cooking time, according to the weight of the foodstuff, and supplies control signals to a turntable motor 4, which turns a turntable 2, to a magnetron 6, which generates microwaves, and to a cooling fan motor 11, which spins a cooling fan 7 to cool the magnetron 6. While the foodstuff 1 is rotated on the turntable 2 , it is cooked by the microwaves which are radiated into a cooking chamber 3 through a waveguide 5.

At the moment the magnetron 6 starts being driven, the controller 15 begins to count time. When the counted time reaches the calculated cooking time, the controller 15 sends control signals to stop the turntable motor 4, the magnetron 6 and the cooking fan motor 11. The respective signals halt the rotation of turntable 2, cease the generation of microwaves and stop the cooling fan 7. This ends the cooking operation.

This method of cooking control, however, does not take into account the state of the food when calculating the cooking time. The food might be frozen or unfrozen, for example.

Another method of controlling the cooking process uses a gas sensor, as shown in Figure 1. A cooking mode is selected using the key input unit and initiated. The mode might be, for example, a program to automatically warm the food. The key input unit sends a corresponding key signal to a controller 15, which starts to count time and also sends appropriate signals to the turntable motor 4, the magnetron 6 and the cooking fan motor 11, as described above.

At the start of this cooking cycle, a gas sensor 10 measures the amount of gas emitted through an outlet 9 and sends a corresponding signal to the controller 15. The controller 15 uses this information to calculate a reference amount. For example, the reference amount might be 75% of the initial amount of emission. The controller 15 continually checks whether amount of emission has reached the reference amount. If it has, a comparison is then made between the counted time and a maximum reference time, which for this cooking mode might be 600 seconds, for example. If the counted time is less than the maximum reference time, the controller 15 sets an initial cooking time value equal to the counted time and then calculates a residual cooking time = initial cooking time x a cooking mode coefficient. The cooking mode coefficient might be 0.4, in this example.

If the counted time has passed the maximum reference time, the controller 15 sets the initial cooking time value to the maximum reference time and then calculates the residual cooking time in a similar fashion.

When the counted time reaches the calculated residual cooking time, the controller 15 sends signals to end the cooking operation, as outlined above.

This method of cooking control, however, uses a pre-established maximum reference time to calculate the initial cooking time, which in turn is used to calculate the residual cooking time. If the amount of gas emission is higher or lower than the actual amount, then this will result in under- or over-cooked food.

The cooking process can also be manually controlled. The cooking parameters, such as the cooking time and temperature, are entered into the key input unit and the process is initiated. The key input unit sends a corresponding key signal to a controller 15, which controls the starting and stopping of the cooking operation, according to the manually input parameters. Once the cooking operation is complete, the controller sends signals to sound a buzzer and operate a display unit.

This method of cooking control, however, relies upon the user to enter the correct cooking parameters. If the user enters too high a temperature or too long a heating cycle, the food may be overcooked.

It is an aim of the present invention to ameliorate the aforementioned problems of the above-described prior art.

According to the present invention, there is provided a method of operating a microwave oven, comprising terminating the cooking of a foodstuff a predetermined time after the time at which a temperature in the region of the foodstuff during cooking reaches a predetermined reference value.

According to the present invention, there is also provided a method of operating a microwave oven, comprising determining a reference time in dependence on the weight of a foodstuff, determining the time at which the level of gas generated during cooking of the foodstuff reaches a predetermined reference level, and if said time exceeds the reference time, cooking the foodstuff for a time which is dependent on the reference time.

According to the present invention, there is also provided a method of operating a microwave oven, comprising selecting a cooking time, terminating the cooking of a foodstuff a predetermined time after the time at which a level of gas generated during cooking reaches a predetermined reference level, so as to override the selected cooking time.

Embodiments of the present invention will now be described, by way of example, with reference to Figures 2 to 8 of the accompanying drawings, in which: Figure 1 is a schematic diagram of a conventional microwave oven; Figure 2 is a schematic block diagram illustrating a microwave oven which implements a cooking control method according to a first embodiment of the present invention; Figure 3 is a flow chart illustrating the operational procedure of cooking control method in a microwave oven according to the first embodiment of the present invention; Figure 4 is a schematic block diagram illustrating a microwave oven which implements a cooking control method according to a second embodiment of the present invention; Figure 5 shows variation of the amount of emitted gas with cooking time; Figure 6 is a flow chart illustrating the operational process of a microwave oven according to the second embodiment of the present invention; Figure 7 is a schematic block diagram illustrating a microwave oven for performing a cooking control method according to a third embodiment of the present invention; and Figure 8 is a flow chart illustrating the operational procedure of cooking control method according to the third embodiment of the present invention.

A first embodiment of the present invention will now be described, by way of example, with reference to the Figures 2 and 3.

Referring to Figure 2, a microwave oven comprises a key input unit 20, a temperature sensor 22, a controller 30, a turntable motor driver 40, a magnetron driver 42 and a cooling fan motor driver 44. The key input unit 20 serves to output an electric key signal corresponding to a cooking mode entered by a user. The temperature sensor 22, mounted in the cooking chamber 3, serves to detect temperature in a cooking chamber and supply a corresponding signal.

The controller 30 sends appropriate control signals to the turntable motor driver 40, magnetron driver 42 and to the cooling fan motor driver 44. These drive the turntable motor 4, magnetron 6 and cooling fan motor 11, which are as shown in Figure 1. In addition, the controller 30 determines whether or not the temperature detected by the temperature sensor 21 has reached a reference temperature. If it has, the controller 30 starts to counts time. When the counted time reaches a residual cooking time, control signals are sent to the turntable motor driver 40, magnetron driver 42 and the cooling fan motor driver 44, which stop the turntable motor, the magnetron and cooling fan motor.

The operation of the above-described microwave oven will now be described with reference to the flow chart in Figure 3.

A cooking mode is selected by the key input unit 20 and initiated. The mode might be, for example, a sequence to automatically warm food. The key input unit 20 sends a corresponding key signal to the controller 30 (step S10).

The controller tests whether a signal to start cooking has been sent. If no such signal is detected then this process is repeated. Once the key signal is identified as a start cooking signal, control signals for driving the turntable motor 4, magnetron 6 and cooling fan motor 11 respectively are output to the turntable motor driver 40, magnetron driver 42 and the cooling fan motor driver 44 (step S20).

As the foodstuff 1 is rotated on the turntable 2 , it is cooked by microwaves generated by the magnetron, which is cooled by the cooling fan (step S30). During this process, the temperature sensor 22 measures the temperature in the cooking chamber and sends a corresponding detected signal to the controller 30 (step S40). The controller 30 tests whether the detected temperature has reached a pre-established reference temperature, appropriate for the cooking mode (step S50). This test is repeated until this condition is satisfied. When the detected temperature reaches the reference temperature, time counting starts (step S60).

The controller 30 repeatedly tests whether the counted time has reached a preestablished residual cooking time, appropriate to the cooking mode (step S70). When the counted time reaches the residual cooking time, cooking is stopped. Control signals for stopping the turntable motor 4, magnetron 6 and cooling fan motor 11 respectively, are sent to the turntable motor driver 40, magnetron driver 42 and the cooling fan motor driver 44 (step S80).

This method of cooking control prevents the foodstuff being undercooked or overcooked, since the temperature of the foodstuff is monitored.

A second embodiment of the present invention will now be described, by way of example, with reference to the Figures 4, 5 and 6.

Referring to Figure 4, a microwave oven comprises a key input unit 50, a gas sensor 52, a weight sensor 54, a controller 60, a turntable motor driver 70, a magnetron driver 72 and a cooling fan motor driver 74. The gas sensor 52 detects the gas generated by the foodstuff while cooking and generates a corresponding gas signal.

The weight sensor 54 detects the weight of the foodstuff and generates a weight signal.

The controller 60 counts time while sending appropriate control signals to the turntable motor driver 70, magnetron driver 72 and cooling motor driver 74. These drive the turntable motor, magnetron and the cooling fan motor.

The controller 60 receives a signal from the weight sensor 54 and calculates a maximum reference time, according to the selected cooking mode. For example, the maximum reference time= 0.3 x weight in grams + 150 seconds, while a minimum reference time is fixed at 70 seconds. The controller 60 also receives the detected signal from the gas sensor 52 and calculates a reference gas amount.

The controller 60 tests whether the gas quantity detected by the gas sensor 52 has reached the reference gas amount. If the detected gas amount has reached the reference gas amount, the controller 60 tests whether the counted time has reached the minimum reference time. If the counted time has not reached the minimum reference time, the controller 60 cooks the foodstuff until the minimum reference time and calculates a residual cooking time, using the counted time as the initial cooking time. If the counted time has passed the minimum reference time, the controller 60 tests whether the counted time has reached the maximum reference time. If the counted time is less than the maximum reference time, then the counted time is used as the initial cooking time. If the counted time is greater than the maximum counted time, then the maximum reference time is used as the initial counted time.

The initial cooking time is then used to calculate the residual cooking time. When the counted time reaches the residual cooking time, control signals are sent to the turntable motor driver 70, magnetron driver 72 and the cooling fan motor driver 74, which stop the turntable motor 4, the magnetron 6 and cooling fan motor 11.

Figure 5 shows the amount of gas emitted with cooking time. The initial cooking time is defined as the period of cooking during which the initial gas amount has not reached a reference gas level. This level might be 75%, for example. The period of cooking when the gas amount is higher than the reference level is defined as the residual cooking time.

The operation of the above-described microwave oven will now be described in detail with reference to the flow chart in Figure 6.

A cooking mode is selected by the key input unit 20 and initiated. The mode might be, for example, a sequence to automatically warm the food. The key input unit 50 sends a corresponding key signal to the controller 60 (step S110).

The controller 60 continually checks for the cooking start signal. If the controller detects the cooking start signal, control signals for driving the turntable motor 4, magnetron 6 and cooling fan motor 11 respectively are sent to the turntable motor driver 70, magnetron driver 72 and the cooling fan motor driver 74 (step S115). As the foodstuff 1 is rotated on the turntable 2 , it is cooked by microwaves generated by the magnetron, which is cooled by the cooling fan (step S120).

From the moment the magnetron is driven, the controller 60 starts counting time (step S125). The weight sensor 54 detects weight of the foodstuff and sends a corresponding signal to the controller 60 (step S130). The controller uses the weight to calculate the maximum reference time = 0.3 x weight in grams+ 150 seconds (stel S135).

The gas sensor 52 detects the amount of gas emitted by the foodstuff as it is cooked and sends a corresponding signal to the controller 60 (step S140). The controller 60 uses this signal to calculate a reference gas amount (75% of the initial gas amount as illustrated in Figure 5) (step S145). The controller 60 continually tests whether the detected gas amount has reached the reference gas amount (step S150). When the detected amount reaches the reference level, a test is then made as to whether the counted time has reached the minimum reference time, in this case 70 seconds (step Sits).

If the counted time has not reached the minimum reference time, the controller 60 cooks the foodstuff up to the minimum reference time (step S160) and uses the counted time as an initial cooking time (step S170). This is used to calculate the residual cooking time = initial cooking time x cooking mode coefficient (0.4) (step S180).

If the counted time has reached the minimum reference time, a test is made to determine whether the counted time has reached the maximum reference time (step S165). If the counted time is less than the maximum reference time, the controller 6C uses the counted time as an initial cooking time (step S170). If the counted time is greater than the maximum reference time, the controller 60 uses the maximum reference time as the initial cooking time (step S175). The initial cooking time is then used to calculate the residual cooking time (step S180). The controller 60 continually tests whether the counted time has reached the calculated residual cooking time (step S185). When the counted time has reached the residual cooking time, control signals for stopping the turntable motor, magnetron and cooling fan motor are sent to the turntable motor driver 70, magnetron driver 72 and the cooling fan motor driver 74 (step 190).

In this way, undercooking or overcooking of the foodstuff is avoided by using the weight of the food and the amount of gas generated to calculate an initial and a residual cooking time.

A third embodiment of the present invention will now be described, by way of example, with reference to the Figures 7 and 8.

Referring to Figure 7, a microwave oven comprises a key input unit 80, a gas sensor 82, a controller 90, a turntable motor driver 100, a magnetron driver 102, a cooling fan motor driver 104, a buzzer 106 and a display unit 108. The controller 90 outputs control signals for driving the turntable motor 4, magnetron 6 and the cooling fan motor 11 respectively according to a key signal input from the key input unit 80, to the turntable motor driver 100, magnetron driver 102 and the cooling fan motor driver 104.

Furthermore, the controller 90 discriminates whether gas amount detected by the gas sensor 82 has reached a reference gas amount, and if the gas amount has reached the reference gas amount, the controller 90 counts time and tests whether the counted time has passed a residual cooking time. If it is determined that the counted time has passed the residual cooking time, the controller 90 respectively outputs to the turntable motor driver 100, magnetron driver 102 and to the cooling fan motor driver 104 control signals for stopping the turntable motor, magnetron and cooling fan motor, and at the same time, outputs control signals to the buzzer 106 and to the display unit 108 for notifying completion of the cooking.

The buzzer 106 generates a cooking completion sound according to the control signal from the controller 90 and the display unit 108 notifies that cooking is complete according to the control signal of the controller 90.

The operation of the above-described microwave oven will now be described with reference to the flow chart in Figure 8.

A cooking mode is manually set up using key input unit 80 and initiated. The mode might include, for example, cooking temperature and time. The key input unit 80 sends a corresponding key signal to the controller 90 (step S210).

The controller 90 continually checks for the cooking start signal. If the controller detects the cooking start signal, control signals for driving the turntable motor 4, magnetron 6 and cooling fan motor 11 respectively are sent to the turntable motor driver 100, magnetron driver 102 and the cooling fan motor driver 104 (step S220).

As the foodstuff 1 is rotated on the turntable 2, it is cooked by microwaves generated by the magnetron, which is cooled by the cooling fan (step S230).

The gas sensor 82 detects the amount of gas generated by the foodstuff during cooking, and sends a corresponding signal to the controller 90 (step S240). The controller tests whether the detected gas amount has reached the pre-established reference gas amount for a boiling foodstuff (step S250). If the detected gas amount has reached the reference gas level, the controller starts counting time (step S260).

The controller 90 then tests whether the counted time has reached a pre-established residual cooking time (step S270). If the counted time has reached the residual cooking time, control signals for stopping the turntable motor, magnetron and cooling fan motor are sent to the turntable motor driver 100, magnetron driver 102 and the cooling fan motor driver 104 (step 280).

In addition, the controller 90 send control signals to the buzzer 106 and to the display unit 108 for notifying completion of the cooking. Successively, the buzzer 106 generates a cooking completion sound and while the display unit 108 simultaneously notifies that cooking is complete to. This finishes the whole cooking operation (step S290).

This method of cooking control prevents the foodstuff being overcooked since the amount of gas generated by the foodstuff is monitored.

Claims

1. A method of operating a microwave oven, comprising: terminating the cooking of a foodstuff a predetermined time after the time at which a temperature in the region of the foodstuff during cooking reaches a predetermined reference value.

2. A method of operating a microwave oven, comprising: determining a reference time in dependence on the weight of a foodstuff; determining the time at which the level of gas generated during cooking of the foodstuff reaches a predetermined reference level; and if said time exceeds the reference time, cooking the foodstuff for a time which is dependent on the reference time.

3. A method according to claim 2, wherein the reference time is calculated as 0.3 times the weight in grams of the foodstuff plus 150 seconds.

4. A method of operating a microwave oven, comprising: selecting a cooking time; terminating the cooking of a foodstuff a predetermined time after the time at which a level of gas generated during cooking reaches a predetermined reference level, so as to override the selected cooking time.

5. A cooking control method of a microwave oven for driving a magnetron to heat and cook foodstuff in a cooking chamber, the method comprising the steps of: driving the magnetron according to a cooking course selected by a user to start heating and cooking the foodstuff; detecting a temperature in the cooking chamber to discriminate whether the detected temperature has reached a reference temperature; counting time to discriminate whether the counted time has passed residual cooking time when the detected time reaches the reference time at the temperature discrimination step; and stopping the magnetron to stop cooking the foodstuff when the counted time passes the residual cooking time at the residual cooking time discrimination step.

6. A cooking control method of a microwave oven for driving a magnetron to heat and cook foodstuff in a cooking chamber, the method comprising the steps of: driving the magnetron according to a cooking course selected by a user to start heating and cooking the foodstuff; detecting a weight of the foodstuff to calculate a maximum reference time; detecting a gas amount generated at the cooking start step and when the detected gas amount reaches a reference gas amount, the counted time is comparatively discriminated with minimum and maximum reference times to thereby calculate an initial cooking time; and stopping the magnetron when the calculated residual cooking time elapses according to the initial cooking time calculated at the initial cooking time calculation step to thereby stop cooking the foodstuff.

7. The method as defined claim 6, wherein the initial cooking time calculation step further comprises the steps of: cooking the foodstuff until the minimum reference time when the counted time does not pass the minimum reference time to thereafter take the counted time as an initial cooking time; taking the counted time as the initial cooking time when the counted time passes the minimum reference time and is less than maximum reference time; and taking the maximum reference time as the initial cooking time when the counted time is not less than maximum reference time

8. The method as defined in claim 6, wherein the maximum reference time is 0.3 X weight of the foodstuff + 150 seconds.

9. A cooking control method of a microwave oven for driving a magnetron to heat and cook foodstuff in a cooking chamber, the method comprising the steps of: driving the magnetron according to a cooking course selected by a user to start heating and heating the foodstuff; detecting the gas amount generated at the cooking start step to discriminate whether the detected gas amount has reached a reference gas amount; counting time when the detected gas amount reaches the reference gas amount to discriminate whether the counted time has passed a residual cooking time; and stopping the magnetron when the time counted at the residual cooking time discrimination step passes the residual cooking time to thereby stop cooking the foodstuff.

10. The method as defined in claim 9, wherein the cooking completion step further comprises the step of generating a cooking completion sound to notify cooking completion and at the same time displaying the cooking completion.

11. A method substantially as hereinbefore described with reference to Figures 3, 6 and 8 of the accompanying drawings.