JPS62168364A - Heating cooker with weight detecting function - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat cooker with a weight detection function that detects the weight of an object to be heated or the amount of change in weight during heating and controls heating. The heat cooker with weight detection function detects the weight of the food before cooking and estimates the cooking end time according to that weight. The finish was detected from information from the temperature sensor and humidity sensor. In particular, when it comes to automatic cooking of oven dishes, there is no effective sensor to detect the finished state, and automatic cooking is mostly achieved using a thermistor-based temperature sensor. FIG. 7 shows the sequence.

1. The interior of the refrigerator is preheated to point A, and the food is stored. Next, let T1 be the time to reach the control temperature after starting cooking at point B, multiply T1 by a predetermined constant K, and set the total cooking time T as T=KT to find the approximate cooking time. In the case of this automatic cooking, the condition is to set the amount of food to a predetermined amount, and if the user makes a mistake in the amount, the T1 time has a drawback that it varies greatly. As a means to overcome this variation in cooking time due to differences in the amount of food, a new method is being considered that detects the finished cooking based on the weight of the food at the start of cooking and changes in weight during cooking.

Problems that the invention seeks to solve 1- However, since general weight detection devices react very sensitively to temperature changes, during heating, that is, when the temperature is fluctuating, fluctuations due to changes in the weight of the food cannot be detected. Is there one?
There is a problem in that it is difficult to determine whether the fluctuation is due to temperature drift ζ of the weight detection device. Furthermore, this temperature drift also varies from weight detection device to weight detection device, so even if it is possible to detect the ambient temperature of the weight detection device, it is not possible to perform optimal temperature compensation for each device. It was extremely difficult to apply the amount of weight change inside to automation of cooking.

Means for Solving the Problems The heat cooker with a weight detection function according to the present invention is equipped with a temperature detection device for detecting the degree of the atmosphere of the weight detection device. The weight of the object to be heated is detected by detecting the elapsed time until the temperature of the atmosphere cooled down by placing the object to be heated returns to the temperature at the time of placing the object to be heated, and the weight of the object at that time. The purpose is to detect the rate of change in weight.

Function: The heat cooker with a weight detection function of the present invention detects the weight of the heated object at two points in time when the ambient temperature of the weight detection device is the same, even during heating. It is possible to accurately measure the weight change rate during heating without any measurement error, and in combination with the initial weight before heating, it is possible to accurately detect the degree of doneness during open heating cooking.

EXAMPLE Hereinafter, a heat cooker with a weight detection function according to an example of the present invention will be described with reference to the drawings. FIG. 2 is a partial cross-sectional view from the side of the heat cooker with a weight detection function. In the donkey pal mechanism, in which the plate spring 5 is fixed in parallel by inserting spacers 11a and 11b, the donkey pal attachment fixed to the lower part of the heating chamber 3 is attached to the plate 1° and becomes a fixed end, and the other end is fixed to the lower part of the heating chamber 3. (on the spacer 11b side) is a free end that is movable in the vertical direction. The door 28 is opened and one object to be heated is placed on the mounting table 2. The mounting table 2 is pivotally supported by #129 of the motor 8 attached to the plate 13. The motor 8 is used to rotate and evenly heat the object 1 to be heated. Now, when the object to be heated 1 is placed, the free end lowers, and the motor is attached to the movable plate 7, which is fixed electrically insulated from the chassis by inserting an insulating plate 9a into the plate 13, and the insulating plate 9b as well. Since the distance between the two electrodes and the fixed plate 6 fixed at the fixed end increases, the capacitance between the two electrode plates becomes smaller. This change in capacitance is transmitted to the weight detection circuit 15 on the printed circuit board 12 via the lead wire 14. The weight detection circuit 15 is disposed close to the upper part of the movable electrode plate 7 and exists in approximately the same atmospheric gradation. Inside the heating chamber 3 is an upper heater 49. and the lower heater 4b, and the internal temperature is detected by the thermistor 2a. A temperature detection circuit 16 is arranged on the printed circuit board 12 to detect the ambient temperature of the printed circuit board 12, the movable electrode plate 7, and the movable electrode plate θ. Signals from the weight detection circuit 15 and the temperature detection circuit 16 are transmitted to a microcomputer 17 that controls the entire heat cooking device with a weight detection function. Fig. 3 shows the circuit diagram of the weight detection circuit, and Fig. 4 shows the control circuit of the heat cooker with the weight detection function. , R2, and the oscillation frequency f of the rectangular wave output of the Schmitt circuit is inversely proportional to the value of C, where VH is the H level of the output voltage and vL is the L level of the output voltage. This waveform is l(5°Dl
, Trl, and R6, the waveform is shaped and input to the microcomputer 17.018 performs dynamic display on the display tube, and 19 is a key matrix for manual input of various keys.To reduce the microcomputer input board, it is scanned from 81 to S4. It is possible to input multiple keys at once. 20 is an oscillation circuit that generates an operating timing clock for the microcomputer, and 21 is an upper and lower heater 4a.
, 4b, 22 is a buzzer for notifying the user, 26 is a heating control relay that turns on and off the heater according to the microcomputer output, 23 is a driver for driving the buzzer 22 and the group of relays, 26 is a door switch that opens a circuit when the door is opened; 24 is a start switch that is linked to a start button; 16 is a temperature detection circuit and an internal temperature detection circuit that detects the internal temperature; 28 is a thermistor. and the A/D input port A/D1. of the microcomputer 17. The temperature of each part is detected by inputting from A/D2.

The signal generated by the weight detection circuit 15 is input to the W port of the microcomputer 17, and is counted by a counter within the microcomputer 17 for a certain period of time to calculate the frequency.

The relationship between the capacitance between the electrode plates 6 and 7, the weight of the object to be heated, and the oscillation frequency of the weight detection circuit is as shown in Figure 6 a + b + C, and the microcomputer 17 stores Figure 5 C. Therefore, the weight is calculated from the counted frequency.

Next, automatic open cooking in the heat cooker with a weight detection function according to the present invention will be explained with reference to FIG. a
is a time chart related to the temperature in the heating chamber, b is a time chart related to the ambient temperature of the weight detection circuit 15 detected by the temperature detection circuit 16, and C is a timing chart related to the weight detected by the weight detection circuit 15, which includes: It also includes errors due to temperature drift in the output of the weight detection circuit 16 due to changes in ambient temperature.

Now, when the user presses the key to select auto cooking related to open cooking and presses the cooking start key, preheating starts.) (Point A) When heating continues, the temperature in heating chamber 3 becomes the same as shown in b. The temperature of the atmosphere in the amount detection circuit 15 continues to rise and when it reaches the set temperature at point B, the buzzer 22 prompts the user to put the food away, and the heating control relay 26.
The temperature inside the heating chamber 3 is controlled to be constant by turning the heater switching relay ON and OFF. As the temperature inside the heating chamber 3 rises, the ambient temperature of the weight detection circuit 16 also rises with a slight delay time as shown in b.

Due to this temperature rise, the weight detection circuit 15 drifts, and as shown in C, the weight changes as if the weight had fluctuated even though no object to be heated is placed between points A and B. When there is an alarm from the buzzer 22 at point B, the door 2
9 is opened (point 0), the door switch 24 is opened, and heating is interrupted, so the temperature inside the refrigerator drops rapidly. Therefore, since the ambient temperature of the weight detection circuit 15 also decreases, the weight changes from the 0 point in the opposite direction to that during heating, as shown in C. When the object to be heated is stored at point D, the weight detected by the weight detection circuit 15 increases as shown by C. This increase W0 corresponds to the initial weight of the object before heating. Thereafter, the door 28 is closed and heating is restarted, but since the initial temperature of the object to be heated is low, the temperature inside the refrigerator further decreases after heating is restarted. Similarly, the ambient temperature of the weight detection circuit decreases, and soon, as the object to be heated begins to heat up, the ambient temperature begins to rise again.

In this way, when the temperature inside the heating chamber and the ambient temperature of the weight detection circuit 15 are fluctuating, it is impossible to distinguish between the weight fluctuation caused by the temperature drift of the circuit and the weight fluctuation caused by water evaporation due to heating. As shown, the temperature of the atmosphere of the weight detection circuit 15 detected by the temperature detection circuit 16 returns to the temperature at the time of initial weight detection at point D. By detecting the weight at point E, accurate heating without temperature drift is achieved. The amount of weight change dW inside can be detected. The initial weight W of the initially heated product detected in this way
The degree of cooking of the food can be detected based on the required time T between 0 and DE points and the weight change idW.

Next, this initial weight W. 9 Weight change amount dW, required time T
Using Figure 6, we will explain how to control the heating time based on 0 taken on the y-axis, and the point where a straight line with a slope of 1△W/T intersects the time axis of the I-axis from point a.The distance from the origin, Ttotal, is the total time until cooking is complete.0
For example, when cooking with a large amount of water evaporation, as typified by cakes, etc., it is necessary to set the value relatively large. Regarding meat dishes, etc., if the water should not evaporate too much due to the cooking quality, please refer to
Optimal cooking can be achieved by experimentally finding values for each category, such as by setting small values.

By doing this, during heating, especially in the oven,
Even when cooking on a grill, where the temperature of the entire set, that is, the atmosphere of the weight detection element or weight detection circuit changes greatly, it is possible to accurately detect the amount of weight change without being affected by temperature drift. Additionally, since there is no need to consider the effects of temperature, conventionally the weight detection element and weight detection circuit had to be installed relatively far from the oven in order to achieve this function. However, in the case of a heat cooker with a weight detection function configured as shown in this example, the dimensions of the machine room at the bottom of the oven have become large, but in the case of the example of the present invention, the weight detection circuit is attached to the oven wall with poor temperature conditions. It is also possible to bring the detection elements close to each other until they reach their respective allowable limit temperatures, making it possible to realize an extremely thin and compact shape.

Effects of the Invention As described above, the heat cooker with a weight detection function of the present invention is equipped with a temperature detection device that detects the temperature of the atmosphere of the weight detection device, and after completion of preheating in the heating chamber, the weight of the heated object placed therein is detected. However, when the ambient temperature of the weight detection circuit cooled by placing the object to be heated returns to the temperature at the time of placing the object to be heated, it detects how much it has decreased and controls the heating time based on the amount of weight reduction. Therefore, no matter how rapidly the ambient temperature of the weight detection element and weight detection circuit changes due to heating during cooking, the temperature remains the same at the time of weight measurement, and an accurate amount of weight change can be detected without being affected by temperature drift. This makes it possible to realize automatic oven cooking that does not require handling of portion sizes.In addition, there is no need to consider the effects of temperature drift; instead, the detection element and detection device should be arranged close to the oven. is possible and the set itself can be made very compact.

[Brief explanation of drawings]

Fig. 1 is a timing chart showing the timing of weight detection by heat cooking with a weight detection function in an embodiment of the present invention, and Fig. 2 is a side view of the heat cooking device with a weight detection function in an embodiment of the present invention. 3 is a circuit diagram of the same weight detection circuit, FIG. 4 is a control circuit diagram of the entire same, and FIG. 6 is a capacitance 1 oscillation frequency between the electrode plates of the same weight detection circuit and a heated object. Figure 6 is an explanatory diagram showing how to calculate cooking time in automatic cooking in the same oven.
FIG. 7 is an explanatory diagram showing conventional cooking. 3... Heating chamber, 4a, 4b... Heater, 6.7... Pole plate, 16... Weight detection circuit, 16...・Temperature detection circuit, 17...
...Microcomputer, 22...Buzzer. Name of agent: Patent attorney Toshio Nakao and one other person? Figure 5 (α) 454L bar iL cooking

Claims (1)

[Claims] A heating chamber, a heating device that heats the object to be heated in the heating chamber, a heating control circuit that stops or controls the heating output of the heating device, and a weight that detects the weight of the object to be heated stored in the heating chamber. The heating control circuit includes a detection device, a temperature detection device that detects the temperature of the atmosphere of the weight detection device, and a preheating means that heats the temperature in the heating chamber to a predetermined temperature, and the heating control circuit is configured to control the weight detection device when the preheating is completed. The weight detected later when the heated object is stored, the elapsed time until the temperature detected by the temperature detection device returns to the vicinity of the temperature at the time of storage of the heated object, and the heated object detected by the weight detection device at that time. A heat cooker with a weight detection function configured to control cooking according to the weight of objects.