JPH0539928A - Heating cooker - Google Patents

Abstract

PURPOSE:To procure reference data indicating zero point, even when a power supply is interrupted, and to prevent degradation of reliability of non-volatile memory. CONSTITUTION:Supplied with power, a microcomputer 1 reads out a reference data from an EEPROM 10, stores it temporarily as a zero point indicating data, and detects a weight of a placed matter based on a frequency signal from a weight sensor 8 with reference to the reference data. At a time of cooking, a zero point is adjusted corresponding to a variation of the zero point of the weight sensor 8, and then the zero point newly adjusted is stored temporarily. If power supply is interrupted, it is detected, and the reference data at that time is rewritten into the EEPROM 10 by extra voltage of a power source circuit. Thus, frequency of rewriting of the reference data is minimized and reliability is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with a weight sensor for detecting the weight when food is placed and the weight when food is not placed on the food table in the heating and cooking chamber. The present invention relates to a heating cooker configured to detect the weight of food based on the weight of the food and control the heating operation, and store the non-placed weight as reference data in a storage unit.

[0002]

2. Description of the Related Art For example, in a microwave oven equipped with a weight sensor, when a food is placed on a turntable in a cooking chamber, the weight of the food is detected by the weight sensor,
The heating and cooking is controlled according to the detected weight.

In this case, the weight sensor, for example, comprises an oscillating circuit including a variable capacitor whose capacity changes according to the weight, and detects the corresponding weight by obtaining the amount of change in the oscillation frequency. ing. Then, when the weight of the food is actually detected, the weight of the food is detected by taking the difference between the weight of only the turntable and the weight when the food is placed.

At this time, since the weight of only the turntable is constant, the detection procedure is simplified by preliminarily measuring and storing it as reference data. However, because the weight of the turntable varies slightly among products, it is not possible to set a value that is common to all products. Therefore, the results of individual measurements are stored in a memory element. ..

Thus, when the weight is measured, the reference data is read from the above-mentioned storage element, so that the weight of the food placed is measured without performing the so-called zero point adjustment for measuring the weight of only the turntable. The weight of the food can be easily detected only by itself.

[0006]

However, in reality, the reference data is changed due to the vibration caused when the heating cooker is shipped as a product and the characteristics of the weight sensor fluctuate as the number of times of use increases. It may shift.

In order to solve such a problem, conventionally, the weight of the turntable is measured every time cooking is performed or at an appropriate time interval, and a temporary storage element such as a RAM is used as new reference data. There is a system in which the zero point is corrected by storing it in.

However, in the case of storing the reference data in the temporary storage element as described above, when the power supply is stopped due to a power failure or the plug being unplugged from the outlet, the corrected reference data is erased. As a result, there is a problem that accurate weight detection cannot be performed.

On the other hand, in order to avoid such a problem, the measured new reference data is not a temporary storage element but a readable / writable non-volatile memory such as an EEPROM.
(Electrical Erasable Programmable ROM) can be used to prevent data loss.
However, in general, since the EEPROM can be rewritten only up to about 10,000 times, for example, if it is rewritten 3 times a day, it will be 10 years, and if it is rewritten 10 times a day, the life will be 3 years. I will end up. In other words, EEPROM
Is originally not suitable for use in which data is frequently rewritten, and in this case, there is a problem that its reliability is lowered.

The present invention has been made in view of the above circumstances, and an object thereof is to ensure reference data indicating a zero point even when power supply is stopped, and even in this case, reliability of the nonvolatile memory is improved. Another object of the present invention is to provide a heating and cooking device having a weight sensor that does not reduce the temperature.

[0011]

SUMMARY OF THE INVENTION The present invention comprises a weight sensor for detecting the weight when food is placed and the weight when food is not placed on the food table of the cooking chamber, and the weight sensor detects the weight. It is intended for a heating cooker that detects the weight of food based on a signal and controls the heating operation, and updates the weight when not placed as needed and stores it in the storage unit as reference data. A readable / writable non-volatile memory for storing the reference data and a rewriting means for rewriting the reference data in the non-volatile memory are provided, and the rewriting means is provided only when power supply is stopped. It is characterized in that the non-volatile memory is configured to write the reference data by an auxiliary power source.

[0012]

According to the cooking device of the present invention, when the power is applied, the rewriting means reads the reference data from the non-volatile memory and uses it for weight detection, and thereafter, while the power is being applied, the cooked food is cooked. The weight sensor detects the weight when no object is placed on the object placing table, that is, when the article is not placed, and the weight is stored in the storage unit as new reference data.
As a result, the reference data of the weight sensor is always stored and held as an appropriate value.

When the power supply is stopped due to a power failure or movement of the device, the reference data at that time is written in the nonvolatile memory by the rewriting means using the auxiliary power source.
The last updated reference data is stored and held, and when the power is supplied next time, the optimum reference data can be used to perform appropriate weight detection. This also allows
The number of rewriting operations to the non-volatile memory is reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention applied to a microwave oven will be described below with reference to the drawings.

In FIG. 1 showing an outline of an electrical configuration, a microcomputer 1 having a memory as a storage section is provided.
Controls heating and cooking according to a program stored in advance and also has a function as a rewriting means, and a DC voltage of 5 V is supplied from the power supply terminal 2. In this case, the power supply terminal 2 is supplied with a DC voltage converted from an AC power supply via a DC power supply circuit (not shown). In addition, the power supply by this DC power supply circuit,
It has a function as an auxiliary power source that temporarily continues power feeding to the power source terminal 2 by a smoothing capacitor even after power feeding from the AC power source is stopped.

A pulse shaping circuit 3, a magnetron drive circuit 4, a turntable drive unit 5, a key input unit 6, a display unit 7, a weight sensor 8 and a clock circuit 9 are connected to the microcomputer 1. An EEPROM 10, which is a readable / writable nonvolatile memory, is connected.

The pulse shaping circuit 3 inverts the level of the pulse output depending on whether the voltage of the AC power supply is positive or negative, thereby generating a power supply pulse corresponding to the frequency and inputting it to the microcomputer 1. The microcomputer 1 always determines the power supply state based on the power supply pulse supplied from the pulse shaping circuit 3 as described later, and obtains a time measurement reference such as a timer.

The magnetron drive circuit 4 oscillates a magnetron (not shown) based on a control signal from the microcomputer 1 to perform a cooking operation. The turntable drive unit 5 rotationally drives the turntable 11 (see FIG. 2), which is a table on which the food is placed, based on a control signal from the microcomputer 1.

The key input section 6 and the display section 7 are arranged on a front panel of the main body (not shown), and the microcomputer 1 outputs control signals to the above sections in response to various operation inputs from the key input section 6. Drive control is performed and a display signal is output to the display unit 7 to display the control state.

In FIG. 2, a sensor support portion 12a is fixed to the lower portion of a bottom plate 12 forming a heating chamber (not shown). A printed circuit board 13a forming a sensor and a leaf spring 13b are arranged at a bottom portion of the sensor support portion 12a at a predetermined distance from the printed circuit board 13a. The printed circuit board 13a and the leaf spring 13b form a variable capacitor 14a.
Is configured.

The rotary shaft 11a of the turntable 11 penetrates through the bottom plate 12 and is projected to the sensor support portion 12a, and its tip end is fixed to the gear portion 11b. This gear part 11
b is received by a leaf spring 13b so as to be vertically movable while penetrating the printed circuit board 13a. In the turntable 11, the rotational force is transmitted to the rotary shaft 11a via the speed reduction mechanism 15a and the gear portion 11b by the rotation of the turntable rotation driving motor 15.

In FIG. 3, the main circuit 16 includes a resistor 16a.
Also, a resistor 16e is connected in parallel to the series circuit of the inverter circuits 16b, 16c and 16d. Then, the variable capacitor 14 is connected in parallel to the series circuit of the resistor 16a and the inverter circuits 16b and 16c to form the weight sensor 8 as an oscillation circuit with variable oscillation frequency.

When a load is applied to the turntable 11, the plate spring 13b is deformed via the gear portion 11b by a change amount according to the load, so that the printed circuit board 13a and the plate spring 13 are deformed.
The distance from b changes. This allows the variable capacitor 14
Since the capacitance of the sensor changes, the oscillation frequency of the weight sensor 8 also changes. The microcomputer 1 can detect the corresponding load by detecting the oscillation frequency.

The EEPROM 10 is supplied with power from the power supply terminal 2, and has four terminals CS, SK, DI and DO connected to the microcomputer 1. In this case, the terminal CS is a read control terminal, the terminal SK is a clock signal input terminal for controlling the timing of serial transmission, and the terminals DI and DO are data input and output terminals from the microcomputer 1, respectively. This EEPRO
In M10, as the reference data previously measured for detecting the weight, the value of the frequency F0 corresponding to the weight when the food is not placed on the turntable 11 and the frequency change amount Δf0 per unit weight. The value of and is written.

Next, the operation of this embodiment will be described together with the control contents of heating and cooking by the microcomputer 1.

First, the weight detection by the weight sensor 8 will be described. As described above, the oscillation frequency F0 of the weight sensor 8 when nothing is placed on the turntable 11 (when not placed) and the frequency change amount Δf per unit weight.
Is written and stored in the EEPROM 10 in advance. Then, when the user first supplies power to the device, the microcomputer 1 reads the data from the EEPROM 10.

When a food item is placed on the turntable 11, the weight sensor 8 gives the microcomputer 1 a frequency signal F indicating the weight of the food item including the weight of the turntable 11. The microcomputer 1 uses the frequency signal F and the oscillation frequency F read from the EEPROM 10.
Based on 0 and the frequency change amount Δf, the weight G of the cooked product is obtained by performing the following calculation.

G (weight of cooked food) = a × (F−F0) / Δf (1) where a is a unit weight which is a standard of Δf.

Next, the control of the microcomputer 1 when the actual cooking is performed will be described according to the cooking control program shown in the flow chart of FIG.

First, when the heating and cooking start switch is turned on, the microcomputer 1 measures the weight G of the food by the method described above (step S1). Then, the heating time T of the cooked food is calculated based on the measured weight G (step S2). In this case, the heating time T is T (heating time) = k × G + m (2) where k and m are constants.

Next, the microcomputer 1 gives a control signal to the magnetron drive circuit 4 and the turntable drive unit 5 to start heating and cooking (step S3). When the heating time T elapses (step S4), the heating and cooking is performed. Exit the program.

Now, as described above, the weight sensor 8 is
As the number of uses increases, the variable capacitor 1
The reference data indicating the oscillation frequency F0 in the non-mounted state may deviate due to aging of the leaf spring 13b of No. 4 and the like. In addition, the present embodiment has a learning function of zero point adjustment for correcting this, and executes the zero point adjustment every time cooking is performed according to the zero point updating program shown in the flowchart in FIG. Then, it will be described below.

That is, when the microcomputer 1 finishes executing the above-described heating and cooking program in step P1, it determines whether or not the door of the heating chamber has been opened (step P2), and thereafter, the above-described weight measurement program. Is carried out (step P3). The result of the measured weight is the weight when the object to be heated is removed, that is, the turntable 1
When the weight is only 1, the microcomputer 1
Determines that it is within the predetermined range (step P4), and the detected weight (oscillation frequency F1) at that time is updated and stored in the storage section inside the microcomputer 1 as reference data indicating a new zero point (step P5). ).

That is, in step P4, it is judged whether or not the food is taken out of the heating chamber. If the food is taken out, the detected weight at that time is the weight of the turntable 11 only, that is, the nonzero reference. This is because it is the weight when placed. Therefore, the microcomputer 1
If "NO" is determined in the step P4, it means that it is not in the non-placed state, and the program is terminated without storing the detected weight at that time as reference data.

However, when the power supply to the apparatus is stopped due to a power failure or the power plug being unplugged, the microcomputer 1 discharges the charging charge of the smoothing capacitor of the DC power supply circuit and the power supply terminal 2 The following operations are carried out until the power supply of is stopped.

The microcomputer 1 always detects the power supply pulse from the pulse shaping circuit 3 in accordance with the program shown in the flow chart of FIG.
In 1 the judgment is “YES” and the program is returned to another program, and the input timing of the power pulse at this time is used as a reference for time measurement (see FIG. 5B).

When the power supply is stopped due to a power failure or the power supply plug being unplugged, the output of the AC power supply disappears as shown in FIG. 5A, and the power supply pulse from the pulse shaping circuit 3 also disappears ( See FIG. 5B). As a result, the microcomputer 1 performs the “YE
S "is determined and the process proceeds to step T2. If the power supply pulse is not detected even at the next detection timing, the microcomputer 1 determines that the power supply is stopped and proceeds to step T3.

When the power supply pulse is detected in step T2, the determination is "NO", the flow returns to step T1, and the power supply pulse is detected again. That is, the stop of the power supply is judged only when the power supply pulse is not detected twice consecutively.

When the power supply is stopped, the terminal voltage of the power supply terminal 2 for supplying the DC power supply to the microcomputer 1 is charged by the smoothing capacitor of the DC power supply circuit (not shown) as described above. It gradually decreases with discharge. At this time, the operating voltage of the microcomputer 1 operates normally within the rated range of 5V to 4.5V, for example, and can be operated for about 0.5 seconds after the AC power supply is stopped (see FIG. 5 (c) and (d)).

Then, in step T3, the microcomputer 1 writes the reference data, which indicates the zero point at that time, that is, the oscillation frequency F1 stored therein, in the EEPROM 10 and ends the program.

Therefore, according to this embodiment, E
Since the oscillation frequency F1 as the last updated reference data is stored and stored in the EPROM 10, when the power is supplied again and the weight detection program is executed, EEPRO
Since the reference data read from M10 has been corrected,
An accurate weight can be detected based on this. Further, such a situation in which the power supply is stopped is rare in a general use state, and therefore the EEPROM 10
The number of times writing operation is performed is extremely reduced, and it is possible to suppress deterioration of the reliability as much as possible.

In the above embodiment, the case where the zero point adjustment is applied to the heating cooker which is performed at the end of cooking has been described, but the present invention is not limited to this, and the zero point adjustment may be performed at any time. Alternatively, the present invention may be applied to one in which the zero point adjustment is appropriately performed by the operation of the user.

[0043]

As described above, according to the heating cooker of the present invention, the reference data at that time is written in the non-volatile memory by using the auxiliary power source by the rewriting means only when the power supply is stopped. Therefore, the weight can always be detected based on appropriate reference data, and even in this case, the frequency of write operations to the nonvolatile memory can be reduced as much as possible, thus reducing the reliability of the nonvolatile memory. It has an excellent effect that it can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an electrical configuration showing an embodiment of the present invention.

FIG. 2 is a vertical sectional side view of a variable capacitor portion of the weight sensor.

FIG. 3 is an electrical configuration diagram of the weight sensor.

FIG. 4 is a flowchart of a reference data rewriting program.

FIG. 5 is a time chart showing an output state of each unit when power supply is stopped.

FIG. 6 is a flowchart of a zero point adjustment program.

FIG. 7: Flow chart of cooking program

[Explanation of symbols]

1 is a microcomputer (rewriting means), 2 is a power supply terminal (auxiliary power supply), 3 is a pulse shaping circuit, 5 is a turntable drive unit, 8 is a weight sensor, 10 is an EEPROM (nonvolatile memory), 11 is a turntable ( An object to be cooked), 14 is a variable capacitor, and 16 is a main circuit.

Claims (1)

[Claims] 1. A weight sensor for detecting a weight when food is placed and a weight when the food is not placed on an object placing table in the heating and cooking chamber, and the weight of the food is determined based on a detection signal from the weight sensor. A readable / writable non-volatile memory for storing the reference data, in which the heating operation is detected and the heating operation is controlled and the non-placed weight is updated at any time to be stored in the storage unit as reference data. And a rewriting means for rewriting the reference data in the non-volatile memory, and the rewriting means writes the reference data in the non-volatile memory by the auxiliary power source only when power supply is stopped. A cooking device characterized by being configured as follows.