JPH0875171A - Heating cooking apparatus - Google Patents

Abstract

PURPOSE: To reduce permanent distortion generated at a leaf spring, to detect an accurate weight, and to control to heat by detecting the weight of a material to be cooked placed on a turntable by an electrostatic capacity type weight sensor having a plurality of the springs. CONSTITUTION: A heating cooking apparatus has an electrostatic capacity type weight sensor 101 for sensing the weight of a material to be cooked, and the sensor 101 has a stationary electrode plate, and a plurality of movable electrode plates made of leaf springs disposed oppositely to the stationary plate. Means 102 for loading the weight of the material to be cooked substantially uniformly to the movable spring electrodes is provided. Thus, since the sensor 101 detects the weight of the material to be cooked placed, for example on a turntable and to be uniformly divided, the durability and the reliability of the sensor 101 are improved. Accordingly, since the detecting error of the sensor 101 is alleviated, the finishing accuracy of heating is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating cooker that cooks food based on the weight of the food.

[0002]

2. Description of the Related Art In recent years, sensor technology applied to heating cookers such as microwave ovens has advanced, and a weight sensor for detecting the weight of a food item placed on a turntable is provided. Since the heating time is set based on the weight and the heating control is performed, the finishing accuracy of the cooking is significantly improved. There are various types of weight sensors of this type, such as capacitance displacement type, pressure displacement type, and differential transformer. Among them, the capacitance type weight sensor (variable capacitance type weight sensor) is most often used. Sensor).

In this electrostatic capacitance type weight sensor, a leaf spring is provided as a movable electrode portion under a turntable and a rotary shaft for receiving a load of food, and a frame of the weight sensor is printed with a fixed electrode portion opposed thereto. A substrate is provided to configure a variable capacitance type capacitor, this capacitor is incorporated into an oscillation circuit, and the oscillation frequency changes according to the change in the gap between the movable electrode part and the fixed electrode part, thereby reducing the weight of the food. It is detecting. However, regardless of which type of weight sensor is applied to the microwave oven, the durability or measurement error of the weight sensor always poses a problem. For example, in a microwave oven using a capacitance type weight sensor, there has been proposed a microwave oven with less measurement error even when used in a high temperature atmosphere (Japanese Utility Model Publication No. 3-31033,
reference).

[0004]

However, the heating cooker using the capacitance type weight sensor has been disclosed in Japanese Utility Model No. 3-31.
As disclosed in Japanese Patent No. 033, even if the measurement error due to high temperature can be reduced by the temperature compensation circuit, the weight of the turntable or the cooked food (food) placed on the turntable. However, since the leaf spring, which is the movable electrode part, is always caught by the rotary shaft (motor shaft) that drives the turntable, permanent hysteresis occurs in the leaf spring due to the residual hysteresis of this weight, and accurate weight can be detected. There is a problem that there is an error in the setting of the heating time. As a result, the finish of cooking may be hindered.

The present invention has been made in consideration of the above circumstances, and in a heating cooker that heats and cooks foods based on the weight of the foods, the weight of the foods placed on the turntable is divided by a plurality of leaf springs. It is intended to provide a heating cooker in which permanent strain generated in a leaf spring is reduced by detecting with a certain capacitance type weight sensor, and accurate weight is detected to control heating.

[0006]

FIG. 1 is a block diagram showing the basic configuration of the present invention. In FIG. 1, the present invention relates to a heating cooker including a capacitance type weight sensor 101 for detecting the weight of an object to be cooked, wherein the weight sensor 101 is
Means 102 configured by a fixed electrode plate and a plurality of movable electrode plates composed of leaf springs arranged to face the fixed electrode plate, and applying the weight of the object to be cooked to the plurality of movable spring electrodes substantially evenly.
A cooking device characterized by being provided with.

The weight sensor 101 is composed of a pair of movable electrode plates which are arranged on the front and back surfaces of a fixed electrode substrate so as to face each other, and a change in electrostatic capacitance between each movable electrode plate and the fixed electrode plate is detected. It is preferable to further include a separate oscillation circuit 103 that outputs a frequency signal and a weight data conversion circuit 104 that converts the frequency signal into weight data.

An average value calculating means 105 for calculating the average value of the two weight data obtained from the separate oscillation circuits 103, and a heating time calculating means 106 for calculating an appropriate heating time based on the average value. It is preferable to have a configuration further including and.

One movable electrode plate is brought into contact with one end of a drive shaft 102a of a turntable on which an object to be cooked is placed, and an intermediate portion of the drive shaft near the one end is moved via the protruding piece 102b. It is preferable that the weight of the food to be cooked including the turntable is transmitted to the movable electrode plates by about half by contacting the electrode plates.

In the present invention, the weight sensor 101
Is provided under the turntable and the rotating shaft that receives the load of the object to be cooked. In addition, the weight sensor 10
1 is a plurality of movable electrode portions composed of a plurality of leaf springs for detecting the weight of the food to be divided substantially evenly, and a plurality of fixed electrode portions corresponding to these movable electrode portions are integrally formed on the front and back surfaces of the double-sided printed circuit board Are formed to form a plurality of sets of variable capacitance capacitors.

Oscillation circuit 103, weight data conversion circuit 10
4. As the average value calculating means 105 and the heating time calculating means 106, a microcomputer including a CPU, a ROM, a RAM, an I / O port, a counter, a timer, a display drive circuit and the like is used. Also, in this ROM,
A signal processing program for converting to weight data, an average value calculation program for calculating the average value from two or more weight data, a heating time calculation program for calculating the heating time corresponding to the average weight, and a heating control for heating and controlling the cooked food. Various programs such as programs and various constants are stored.

[0012]

According to the structure of the present invention, in FIG. 1, in the heating cooker provided with the capacitance type weight sensor 101 for detecting the weight of the object to be cooked, the weight sensor 101 is provided on the fixed electrode plate and the fixed electrode plate. The weight sensor is composed of a plurality of movable electrode plates composed of leaf springs arranged opposite to each other, and means 102 for applying the weight of the object to be cooked to the plurality of movable spring electrodes substantially evenly is provided. For example, since the weight of the food to be cooked placed on the turntable is equally divided and detected, the durability and reliability of the weight sensor are improved. Therefore, the detection error of the weight sensor is reduced, and the heating accuracy is improved.

The weight sensor 101 is composed of a pair of movable electrode plates arranged on the front and back surfaces of a fixed electrode substrate so as to face each other, and a change in electrostatic capacitance between each movable electrode plate and the fixed electrode plate is detected. If a configuration is further provided in which each separate oscillation circuit 103 that outputs as a frequency signal and a weight data conversion circuit 104 that converts this frequency signal into weight data are provided, weight data can be individually obtained from two capacitance displacements. You can ask.

An average value calculating means 105 for calculating an average value of the two weight data obtained from the separate oscillation circuits 103, and a heating time calculating means 106 for calculating an appropriate heating time based on the average value. If the configuration is further provided with, the heating time is calculated based on the average value of the two weight data and the heating is controlled, so that the finishing accuracy of heating is improved.

One movable electrode plate is brought into contact with one end of the drive shaft 102a of the turntable on which the object to be cooked is placed, and the intermediate portion of the drive shaft near the one end is moved via the protrusion 102b. If the weight of the food to be cooked including the turntable is transferred to the movable electrode plates by about half by contacting the electrode plate, the weight of the food to be cooked placed on the turntable Is detected evenly, it is possible to reduce the detection error due to the permanent deformation of the leaf spring. Therefore, the durability and reliability of the weight sensor are improved.

[0016]

The present invention will be described in detail below based on the embodiments shown in the drawings. The present invention is not limited to this. INDUSTRIAL APPLICABILITY The present invention is mainly suitable for use in a heating cooker that cooks food based on the weight of the food. In addition to achieving a "heating cooker that detects the weight accurately by reducing the detection error of the weight sensor," each component is an electrical appliance that requires highly accurate weight measurement using a capacitance-type weight sensor. It can also be applied to all areas.

FIG. 2 is a block diagram showing an embodiment of the heating cooker according to the present invention. In FIG. 2, reference numeral 1 is a turntable that prevents uneven heating of the food. Reference numeral 2 is a weight sensor having two capacitance-type capacitors C1 and C2, and is provided below the turntable 1 and the rotating shaft (motor shaft) that receives the load of the food. 3a, 3
b incorporates these capacitance type capacitors C1 and C2,
A first oscillating circuit and a second oscillating circuit that change an oscillating frequency according to a change in capacitance, and divide the weight of the cooked product into halves to detect two frequency signals.

Reference numeral 4 denotes a control unit, and the control unit 4 has a C
Microcomputer 4 including PU, ROM, RAM, I / O port, counter, timer, display drive circuit, etc.
a. Further, in this ROM, a signal processing program for processing weight data from frequency signals, an average value calculation program for calculating an average value from two weight data, a heating time calculation program for calculating a heating time corresponding to the average weight, Various programs such as a heating control program for heating and controlling cooked food, various constants, and the like are stored.
Further, the weight of the cooked food is divided into two pieces of weight data and stored in this RAM.

Reference numeral 5 is a heating unit for heating and cooking the food,
It is composed of a magnetron 5a that oscillates a high frequency and a heater 5b that heats the oven. Reference numeral 6 denotes a load control circuit for controlling the magnetron 5a, the heater 5b, the geared motor 1a for rotationally driving the turntable 1, and the like, which is connected to the output port of the microcomputer 4a. The first and second oscillator circuits 3a and 3b are connected to the input port of the microcomputer of the control unit 4. The two oscillating frequencies input are the microcomputer 4
It is converted into two weight data by two counters and a signal processing program built in a.

The microcomputer 4a of the control unit 4 is
From the two weight data, the weight calculation program calculates the average value, and the heating time calculation program calculates the heating time corresponding to the average weight to control the heating unit 5. A timer built in the microcomputer 4a is used as a means for measuring the heating time of the heating unit 5. Reference numeral 6 is a key input unit for inputting a menu and heating conditions, and a touch panel and a keyboard are used. Reference numeral 7 is a display unit for displaying a menu, a heating time and the like which are key-inputted, and a fluorescent display tube is used. The key input section 7 and the display section 8 are connected to the input / output port of the microcomputer 4a. The display unit 8 is driven by the display drive circuit built in the microcomputer 4a.

FIG. 3 is a schematic sectional view showing the structure of the weight sensor of the present invention. In FIG. 3, 11 is a shaft, 21
Is a frame of the weight sensor 2 and 22 is two fixed electrode parts 2
2a and 22b are printed on both front and back surfaces, a double-sided printed circuit board 23a is an upper leaf spring functioning as a movable electrode portion corresponding to a fixed electrode on the front surface, and a lower portion 23b is a lower electrode functioning as a movable electrode portion corresponding to a fixed electrode portion on the back surface. It is a leaf spring. Reference numeral 12 is a protrusion (projection piece) for transmitting a load of 1/2 of the food placed on the turntable 1 to the upper leaf spring 23a, and is fixed to the shaft 11 of the turntable 1 in an adjustable manner. . Further, the remaining half of the load is transmitted to the lower leaf spring 23b via the shaft 11. That is, the fixed electrode 22 on the surface of the double-sided printed circuit board 22.
a and the upper leaf spring 23a constitute a variable capacitance capacitor C1, the fixed electrode 22b on the back surface of the double-sided printed circuit board 22 and the lower leaf spring 23b constitute a variable capacitance capacitor C2, and the variable capacitance capacitors C1 and C2 make up the total weight. 1/2 of each is converted into capacitance displacement.

FIG. 4 is a circuit diagram showing an example of an oscillator circuit applied to a weight sensor. As shown in FIG. 4, the three-stage inverters I1, I2, I3 and the variable capacitor C constitute an oscillating circuit with resistors R, Rs, whereby an oscillating frequency represented by the following equation is generated. Further, Rs is a current limiting resistor, which is usually 10 and several kΩ. The relationship of f (oscillation frequency) = 1 / 2.2CR is established. The output terminal of the oscillator circuit is connected to the input port of the microcomputer, processed by the counter incorporated in the microcomputer into weight data, and stored in the RAM. In the embodiment shown in FIG. 2, the oscillation circuit shown in FIG.
Two first oscillator circuits 3a and two second oscillator circuits 3b are provided.

FIG. 5 is an explanatory diagram showing the relationship between the detected weight and the frequency. Half of the weight of the food placed on the turntable 1 is applied to the upper leaf spring 23a through the protrusion 12 and at the same time, the other half is applied to the lower leaf spring 23b. At this time, the gap (variable capacitance C1) between the upper leaf spring 23a and the fixed electrode portion on the front side becomes narrower, and the gap between the lower leaf spring 23b and the fixed electrode portion on the back side becomes smaller.
Since the (variable capacitance C2) expands, the relationship between the frequency obtained from the variable capacitances C1 and C2 between the leaf spring and the fixed electrode portion and the detected weight is reversed as shown in FIG.

FIG. 6 is a flow chart showing an embodiment of heating control processing to which the weight sensor of the present invention is applied. Figure 6
Weight detection and heating control will be described with reference to the flowchart of FIG. Step S01: When the cooking start key is pressed, the geared motor 1a is turned on and the turntable 1 is rotated. Step S02: Initialize the RAM to check whether the weight of the weight sensor 2 can be detected. Step S03: The oscillation frequency f1 due to the capacitance displacement of the upper leaf spring 23a and the fixed electrode and the oscillation frequency f2 due to the capacitance displacement of the lower leaf spring 23b and the fixed electrode are respectively counted, and two oscillation frequencies f1 and f2 are counted. It is converted into weight data w1 and w2. Here, the weight data is detected by dividing the weight of the food into halves, but is doubled and stored in the RAM as weight data W1 and W2 of the total weight.

Step S04: These two weight data W
The average weight Wm = (W1 + W2) / 2 is calculated from the values of 1 and W2. Step S05: When the heating time is calculated from the value of the average weight Wm, the timer is set and the heating unit 5 is driven. Step S06: When the heating time is over, the driving of the heating unit 5 is stopped, the geared motor 1a is turned off, the rotation of the turntable 1 is stopped, and the cooking is completed.

As described above, since the weight sensor 2 detects the weight of the cooked food placed on the turntable 1 by dividing it into halves, the durability and reliability of the weight sensor are improved. Therefore, the detection error of the weight sensor is reduced, and the finishing accuracy of cooking is improved. Further, in the above embodiment, the heating control has been described using the capacitance type weight sensor having two leaf springs (movable spring electrodes), but the capacitance type weight sensor having two or more leaf springs is configured. You may. In this case, if the configuration of the means for applying a load to the plurality of leaf springs substantially evenly, the oscillation circuit, the weight data conversion circuit, etc. is taken into consideration, a weight sensor with further improved durability and reliability can be obtained. , The finishing accuracy of cooking is improved. .

[0027]

According to the present invention, in the heating cooker for cooking based on the weight of the food, the capacitance type weight sensor having the plurality of leaf springs for the weight of the food placed on the turntable is provided. By detecting with, the permanent deformation of the leaf spring is reduced, and the accurate weight is detected. Therefore, the detection error of the weight sensor is reduced, and the finishing accuracy of cooking is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of the present invention.

FIG. 2 is a block diagram showing an embodiment of the heating cooker according to the present invention.

FIG. 3 is a schematic cross-sectional view showing the structure of the weight sensor of the present invention.

FIG. 4 is a circuit diagram showing an example of an oscillation circuit applied to a weight sensor.

FIG. 5 is an explanatory diagram showing a relationship between detected weight and frequency.

FIG. 6 is a flowchart showing an example of a heating control process to which the weight sensor of the present invention is applied.

[Explanation of symbols]

1 Turntable (Gard Motor 1a) 2 Weight Sensor 3a First Oscillation Circuit 3b Second Oscillation Circuit 4 Control Section (Microcomputer 4a) 5 Heating Section (Magntron 5a, Heater 5b) 6 Load Control Circuit 7 Key Input Section 8 Display Section 11 Shaft 12 Projection 21 Frame 22 Double-sided printed circuit board (fixed electrode portions 22a, 22
b) 23a upper leaf spring 23b lower leaf spring

Claims (4)

[Claims] 1. A heating cooker equipped with a capacitance type weight sensor for detecting the weight of an object to be cooked, wherein the weight sensor comprises a plurality of movable electrodes composed of a fixed electrode plate and a leaf spring arranged to face the fixed electrode plate. Composed of an electrode plate,
A heating cooker characterized in that means for applying the weight of the object to be cooked to the plurality of movable spring electrodes substantially evenly is provided. 2. The weight sensor is constituted by a pair of movable electrode plates which are arranged on the front and back surfaces of a fixed electrode substrate so as to face each other, and a change in electrostatic capacitance between each movable electrode plate and the fixed electrode plate. The heating cooker according to claim 1, further comprising: a separate oscillation circuit that outputs the frequency signal as a frequency signal, and a weight data conversion circuit that converts the frequency signal into weight data. 3. An average value calculating means for calculating an average value of the two weight data obtained from the separate oscillation circuits, and a heating time calculating means for calculating an appropriate heating time based on the average value. The cooking device according to claim 2, further comprising: 4. A movable electrode plate of one side is brought into contact with one end of a drive shaft of a turntable on which an object to be cooked is placed, and an intermediate portion of the drive shaft near the one end is movable via a projecting piece. The heating cooker according to claim 2, wherein the weight of the object to be cooked including the turntable is transmitted to the movable electrode plates by about half by being brought into contact with the electrode plates.