JPS59138827A - Microwave oven - Google Patents

Abstract

PURPOSE:To secure the same cooking period independent of the surrounding humidity so as to secure constant cooking condition regardless of the surrounding humidity, by changing the level of detection point of a comparator for the time of completion of cooking, said comparator being for detecting, in accordance with the surrounding humidity, the fact that the output of a cooking sensor reaches a cooking completion level. CONSTITUTION:After smell or steam remaining in a microwave oven is discharged, and before cooking is started, an arithmetic control 5 detects the surrounding humidity of the cooking sensor R5 from the output value of an A/D converter 3, and based on this detected value of the surrounding humidity, outputs a reference value Vk of a comparator 4 at the time of completion of cooking to this comparator 4. When the digital output of the output VS of the cooking sensor RS inputted from the A/D converter becomes the reference value VK, the arithmetic control 5 receives a signal outputted from the comparator 4 so that drivers 7, 8 are turned OFF to deenergize relays RY1, RY2.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a microwave oven having a function of detecting the progress of cooking using a cooking sensor such as a gas sensor or a humidity sensor.

<Prior Art> Generally, the amount of water vapor and gas generated when cooking food in a microwave oven remains approximately constant once the type and amount of food are determined. For example, when broccoli is cooked in a microwave oven, the absolute humidity at the location where the cooking sensor is placed is approximately 60g, as shown by curve h1 in Figure 1.
/m”. In the above-mentioned FIG. This is because gas is released from the broccoli before steam is released.

By the way, the environmental humidity in which a microwave oven is installed varies from approximately 2 fl/m3 to approximately 309/m3 depending on the climate and seasons, but there is a difference between the resistance value of the cooking sensor and the absolute humidity as shown in Figure 2. Therefore, when the environmental humidity is 11 g/rn', for example, when cooking broccoli, the resistance of the cooking sensor changes by 55 kilo ohms from 4i11 dlOO kilo ohms to 45 kilo ohms, while the environmental humidity is 309 When cooking in the /rn' state, the resistance value of the cooking sensor changes only by -Q7 kilohms from 62 kilohms to 45 kilohms.

The cooking sensor, as shown by R5 in FIG.
The potential with respect to ground is VREF through the load resistor RLf.
Connected between power line 2 and ground,
When broccoli is cooked in an environment of 11 f//rn3 with RL = 50 kilohms, the output Vs of the cooking sensor R5 changes by 22% from 100% to 78%, as shown by curve h3 in Fig. 4. On the other hand, when cooking in an environment of 30 g/m', the output V5 changes by only 15% from 100% to 85%, as shown by curve h4 in FIG. That is, the rate of change of the output V5 changes depending on the environmental humidity.

By the way, in conventional microwave ovens, the cooking time is the time required for the rate of change to change by 10%, for example from 100% to 90%. As you can see by comparing the times, the environmental humidity is 119
/ m" and 30 g/m3, there is a ΔT difference in cooking time. Therefore, if the environmental humidity is high, the result will be overcooked, and conversely, if the environmental humidity is low, the result will be undercooked. There was a problem.

<Purpose> The present invention has been made to solve the above-mentioned problems in conventional microwave ovens.The purpose of the present invention is to provide an arithmetic control circuit that detects environmental humidity from the output of a cooking sensor, and to By changing the detection point level at the completion of cooking of the comparator that detects when the output of the cooking sensor has reached the cooking end level, the cooking time is the same regardless of the environmental humidity, and the cooking time is the same regardless of the surrounding environmental humidity. The objective is to be able to obtain a constant cooking finish without being affected.

<Summary of the Invention> To summarize the present invention, there is provided a microwave oven equipped with a function of detecting the progress of cooking using a cooking sensor such as a gas sensor or a humidity sensor, which detects the output of the cooking sensor and a standard for the completion of cooking. The environmental humidity around the sensor is detected from the comparator that determines the magnitude of the value, and the output of the cooking sensor after the odor and water vapor remaining inside the microwave oven are discharged at the start of cooking. A calculation control circuit that calculates the reference value of the comparator at the time of cooking completion from the detected value, and terminates the cooking operation by a signal output from the comparator when the output of the cooking sensor reaches the reference value. This microwave oven is characterized in that the detection point level of the comparator at the time of cooking completion is changed depending on the state of the environmental humidity.

<Example> Hereinafter, the present invention will be fully described in detail with reference to the accompanying drawings.

A block diagram is shown.

In FIG. 5, R5 is a cooking sensor, RL is a load of the cooking sensor R5, 3 is an A/D converter that converts the output Vs of the cooking sensor Rs into a digital signal, 4 is a comparator, 5 is an arithmetic control circuit, 6 is a keyboard for inputting various cooking information such as the menu, the type and amount of food to be cooked, or various command information such as starting or stopping cooking to the arithmetic and control circuit 5; 7 is a driver for driving the relay RY1; , 8 is a driver for driving another relay RY2, 9 is a display element, and the relay RY1 turns on and off electricity to a cleaning fan (not shown), a turn-chip pull motor, an oven lamp, etc. RY2 controls microwave generation.

The cooking sensor R5 includes a heater 10 and a sensor section 11. The heater 10 is connected to a heater power source (not shown), while the sensor section 11 is connected in series with a load resistor RL between a power source vREF and ground. ing.

The output Vs output from between the connection point 12 between the sensor section 11 and the load resistor RL and the ground is the A/D converter 3
The output Vs, which is input to the A/D converter 3 and digitized by the A/D converter 3, is input to the comparator 4 and the arithmetic control circuit 5.

The arithmetic control circuit 5 determines the cooking sensor R5 based on the output value of the A/D converter 3 after exhausting odor and water vapor remaining in the maven (not shown) of the microwave oven at the start of cooking, based on the relationship shown in FIG. The surrounding environmental humidity is detected, and from the detected value of this environmental humidity, as described later, a reference value Vk of the comparator 4 at the time of cooking completion is calculated, and this reference value k is output to the ratio 1 bite device 4. do.

Further, the arithmetic control circuit 5 receives a digital output (
Hereinafter, this will be referred to as output V5. ) reaches the reference value (2), the drivers 7 and 8 are turned off in response to the signal output from the comparator 4, and the relays RY1 and RY2 are deenergized.

Next, the operation of the control device shown in FIG. 5 will be explained with reference to the flowchart shown in FIG.

In step 101, when the cooking start signal is input from the keep machine, the arithmetic control circuit 5 executes step 102, turns on the driver 7, energizes the relay RY12, and rotates the turntable motor (not shown). , turn on the oven light and begin the cleaning cycle. During this cleaning cycle, the arithmetic control circuit 5, in step 103, removes the output V of the cooking sensor r (5 from the A/D converter 3).
Read the 5f digital father exchanger output V5, then,
In step 101ζ, the resistance value ks of the sensor section 11 of the cooking sensor R5 at this point in time is calculated.

In addition, the above resistance value R3 is R5=RLVs/(VREF
-vS), and since "L" and vREF are known constants, the resistance value R5 can be calculated from the output Vs as described above.

By the way, the resistance value RS of the sensor unit 11 with respect to environmental humidity
is determined experimentally as shown in Fig. 2, and the resistance fiI of the sensor section 11 after the completion of the cleaning cycle is
□, the output vs is Vsl, and the ratio of the output vs at the detection point of mm finish and the above output Vs1 is K, then the relational expression K, , = f(R5□) holds true.

In step 105, the arithmetic control circuit 5 calculates K-[(R8
From the above ratio determined by 1) and the above output Vs i, v
The calculation k=Kxvs□ is executed to calculate the reference value Vk of the comparator 4 at the time of cooking completion.

Next, the arithmetic control circuit 5 determines whether or not the cleaning time has ended in step 106. If the cleaning time has ended, step 10'7 is executed; if the cleaning time has not ended, Return to step 103.

In step 107, the arithmetic control circuit 5 turns on the driver 8, energizes the relay RY2, generates microwaves, and starts heating.

Next, the arithmetic control circuit 5 measures the elapsed time T1 from the time of generation of the microwave until Vs becomes less than Vk, step 108, and reads the output Vs in step 10.
9. Step 11 of determining whether Vs<■ is true or not
0 in sequence.

When Vs becomes less than Vk, the arithmetic control circuit 5 executes step 111, calculates T2=TzxN based on the elapsed time T1 from the microwave generation to the time when V5<Vk, and calculates the additional heat time T2. Calculate. However, the above N
is a constant called the additive heat constant, which has been experimentally determined to be optimal for finishing the cooking of each food.

The arithmetic and control circuit 5 executes steps 112 and 113 to perform additional heating only during the additional heating time T2.

When the additional heating time T2 has elapsed, in step 114 the five-piece arithmetic and control circuit drivers 7 and 8 are turned off.
RY1 and RY2 are de-energized and the cooking ends in step 115.

As can be seen from the above operation description, if the environmental humidity is, for example, 1
1///rl, the reference value Vk of comparator 4 is set to 85%, and the environmental humidity is, for example, 301//Tl.
In this case, if the reference value vk of the comparator 4 is set to 94.5%, the cooking time will be the same as shown in Figure 4, and a constant cooking finish will be obtained without being affected by the surrounding environmental humidity. It will be done.

In the above embodiments, the arithmetic control circuit 5 is preferably configured by a microcomputer, but the present invention is not limited thereto.

Effect> As is clear from the detailed description above, the present invention has the following effects:
In microwave ovens equipped with a function to detect the progress of cooking using a cooking sensor, the detection point level at the time of cooking completion is changed according to the environmental humidity. Regardless, the cooking time is the same, and good cooking results can be obtained without being affected by environmental humidity.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the relationship between microwave cooking time, absolute humidity detected by a cooking sensor, and voltage ratio across the sensor; Figure 2 is an explanatory diagram showing the relationship between sensor resistance and absolute humidity; Figure 4 is a circuit diagram of the cooking sensor, Figure 4 is an explanatory diagram showing the relationship between the detection time of finished cooking and the rate of change in voltage across the cooking sensor, Figure 5 is a block diagram of the microwave oven according to the present invention, and Figure 6 is 6 is a flowchart of the operation of the microwave oven of FIG. 5. R5...Cooking sensor, RL...Load resistance, 3...
A/D converter, 4... Comparator, 5... Arithmetic control circuit, 6... Keyboard, 7, 8... Driver, 9
...Display element. Patent applicant: Sharp Co., Ltd. Patent attorney Hajime Aoyama and 2 others

Claims (1)

[Claims] (1) A microwave oven equipped with a function to detect the progress of cooking using a cooking sensor such as a gas sensor or a humidity sensor, which determines the magnitude of the output of the cooking sensor and a reference value at the time of finishing cooking. The ambient humidity around the sensor is detected from the comparator and the first output of the cooking sensor after the odor and water vapor remaining inside the microwave oven are discharged at the start of cooking, and the detected value of the environmental humidity is used to determine when the cooking is finished. an arithmetic control circuit that calculates the reference value of the comparator and terminates the cooking operation by a signal output from the comparator when the output of the cooking sensor reaches the reference value, A microwave oven characterized in that a detection point level of a comparator at the time of cooking completion is changed depending on the state of the microwave oven.