KR950002482B1 - Weight-measuring apparatus for a microwave range - Google Patents

Abstract

The method includes the steps of judging the operation state of a weight sensor when food is put on a glass tray of a microwave oven, storing the sensing value as a digital value and counting the number of counting times, resetting the sensor if the number of sensing times is 1, and if not, storing its maximum and minimum values, obtaining the deviation of the sensor output if the number of sensing times is in deviation period, judging an eccentricity load if the number of sensing times is twice the deviation period, storing the mean value of the sensor if the number of sensing times is the final number, judging error using the mean value of the sensor, judging the eccentricity load after error is judged, if eccentricity load state, compensating it and storing it as a sensor value, and performing automatic thawing function.

Description

Microwave Food Weight Detection Method

1 is a block diagram of a conventional microwave food weight sensing device.

2 is a detailed view of the food weight detection unit of a typical microwave oven.

3 is a detailed circuit diagram of each part of FIG.

4 is an output waveform diagram of a sensor in detecting food weight.

A to d in FIG. 5 are operational waveform diagrams for parts of FIG.

6 is a conventional microwave food weight sensor signal flow chart.

7 is a signal flow diagram of the microwave food weight detection of the present invention.

8 is a schematic diagram of a microcomputer for carrying out the present invention.

* Explanation of symbols for main parts of the drawings

1 sensor 2 amplification unit

3: reset section 4: analog / digital converter

5: timer 6: analog / digital counter

7: input / output controller 10: microcomputer

11: glass tray 12: roller

13: plate R ₁ ~R _5: Resistance

VR ₁ : Variable resistor OP _{1 to} OP ₂ : Operational Amplifier

C _{1 ~} C ₂ : Capacitor D ₁ : Diode

Q ₁ : Transistor.

The present invention relates to a food weight sensing method of a microwave oven using a piezo sensor, and in particular, when an eccentric load is applied to a glass tray, it detects heavier than the actual weight and prevents a malfunction of lengthening an automatic thawing time longer than a load. The present invention relates to a food weight sensing method of a microwave oven that is suitable for improving the range performance.

1 is a configuration diagram of a conventional microwave food weight sensing device, as shown in FIG. 1, a sensor for sensing weight by a piezoelectric effect in which electrical polarization occurs when a food to be cooked is subjected to stress on a solid crystal. (1), an amplifier 2 for amplifying a voltage corresponding to the food weight of the sensor 1 and latching it for a predetermined time, and an analog output signal of the amplifier 2 is applied to It consists of a microcomputer 10 for calculating the weight and controlling the overall system of the microwave oven and a reset unit 3 for resetting the operation of the medium width unit 2 by the control signal of the microcomputer 10. The microcomputer 10 receives an analog output signal of the amplifier 2 and converts the digital signal into a digital signal, and the number of digital conversion times of the analog / digital converter 4. An analog / digital conversion counter (6) for counting the number of times, a timer (5) for setting an operation time to adjust the operation time, the timer (5), and an output signal from the analog / digital converter (4) It is composed of an input and output control unit 7 for controlling the input and output of the microcomputer 10 by calculating the weight of food.

2 is a detailed view of the food weight sensing unit of a conventional microwave oven, as shown therein, a groove is formed at a position where the leakage of microwaves is smallest on the plate 13 supporting the food sensing unit, and a sensor which is a piezoelectric element in the groove ( 1) is mounted and the roller 12 is rotated by a motor on the plate 13, the glass tray 11 for supporting food on the roller 12 is mounted and the glass train 11 is number 2 When rotating, the roller 12 is configured to sense the weight by pressing the sensor 1 three times.

FIG. 3 is a detailed circuit diagram of each part of the food sensing device of the microwave oven. As shown therein, the resistors R ₁ to R ₂ and the condenser C _{1 of the} sensor 1 and the amplifying unit 2 are OP amplifiers. ₁ ) is connected to the non-inverting input terminal (+), and the grounding resistor (R ₃ ) and the variable resistor (VR ₁ ) are commonly connected to the inverting input terminal (-) and the output terminal of the associating amplifier (OP ₁ ). an output terminal of the operational amplifier (OP ₁₎ is connected to a resistor (R ₄₎ and the non-inverting input terminal (+) of the operational amplifier (OP ₂₎ through the diode (D _1), sequentially, the non-inverting input terminal (+) The capacitor C ₂ and the collector of the transistor Q _{1 of the} latch portion 3 are connected to each other, and the reset input terminal R through the resistor R ₅ is connected to the base of the transistor Q ₁ . The inverting input terminal (-) of the amplifier OP ₂ is configured to be connected to its output terminal.

The operation process and problems of the conventional food weight sensing apparatus configured as described above will be described with reference to FIGS. 4 to 6.

When the user puts food on the glass tray 11 of the microwave oven to cook food and operates the automatic thawing key, the main relay is turned on, and when the glass tray 11 is rotated by the motor, the lamp in the refrigerator is turned on.

At this time, the microcomputer 10 controls the reset unit 3 to reset and initialize the amplifier 2.

When the glass tray 11 is rotated as shown in FIG. 2, the roller 12 accordingly presses the sensor 1 while following the rotational trajectory of the glass tray 11 and accordingly the sensor 1. ) Generates an output voltage equal to the waveform shown in FIG. 4 by the piezoelectric sensor.

Applying the same waveform as that of the fifth degree a by the operation of the always-sensor (1) to a third-degree operational amplifier (OP ₁₎ the non-inverting input terminal (+) and the operational amplifier (OP ₂₎ has a resistance (R ₃₎ and Non-inverted and amplified by the ratio of the variable resistor VR ₁ to output the same waveform as b in FIG. 5 to obtain a time constant through the resistor R ₄ and the diode D ₁ . ) Is charged to the capacitor C ₂ with the voltage having the same waveform as c in FIG. 5.

At this time, the capacitor (C _2), the charge does not have a voltage change occurs no discharge path to the operational amplifier (OP ₂₎ applied to the non-inverting input terminal (+) to the operational amplifier (OP ₂₎ of the degree of claim 5 d filled in Outputs a signal having the same waveform as and applies it to the analog / digital converter 4 of the microcomputer 10 of FIG. The weight sensing signal is converted into a digital signal and applied to the input / output control unit 7.

The input-output controller (7) is a timer (5) hanhu the time the operation during the set in FIG. 2 the reset unit 3, the transistor is applied to the high potential signal to the base of (Q _1), and this causes the transistor (Q ₁ ) Is turned on to discharge the electric charge charged in the capacitor C _{2 of} the amplifier 2 to reset the amplifier 2.

After that, the analog / digital counter 6 counts the number of times the roller 12 presses the sensor 1, and judges the output value of the analog / digital counter 6, and if it is “1”, the roller 12 is in the initial state. (1) is pressed and the output value of the sensor 1 is discarded and the output of the sensor 1 is reset in the same manner as described above, while the value of the analog / digital counter 6 is " 1 " Otherwise, the counter value is continuously accumulated, and the analog / digital counter 6 determines whether the value is "17". If not, the amplifier 12 resets the amplification unit 2 as described above, and the roller 12 In the step of confirming whether or not (1) has been pressed, and if the value of the analog / digital counter 6 is "17", the counted value is divided by 16, averaged, and the value is compared with the glass tray 11. , Or if it is greater than the maximum weight, reset it If greater than the weight of the tray 11 is smaller than the maximum weight by converting the defrosting time to perform an automatic thawing function.

The conventional food weight sensing method of the conventional microwave oven operates as described above when the weight of the food to be defrosted is placed in the center of the microwave glass tray and eccentrically to one side. There was a problem in that it causes the malfunction of the microwave oven to reduce the performance.

In the microwave food weight sensing method of the present invention in consideration of such a conventional problem, the deviation between the maximum value and the maximum value and the minimum value in the analog / digital conversion value of the sensor is integrated and judged whether the eccentric load is applied to the eccentric load. In this case, the error of the weight due to the eccentric load is compensated in a specific way to accurately detect the weight and improve the performance of the microwave oven.

8 is an internal configuration diagram of a microcomputer for carrying out the present invention. As shown therein, when food is applied to a microwave oven, the sensor 1 detects the load of the food, and the amplification amplifies the output value of the sensor 1. The microcomputer 10, which receives the output signal from the amplifying unit 2, judges the weight of food and performs the overall functions of the microwave oven accordingly, and controls the microcomputer 10. The microcomputer 10 converts the output of the amplification unit 2 into digital, and operates the analog / digital converter 4 to reset the amplifying unit 2. A timer 5 for setting a time, a counter 6 for counting the number of conversions of the analog / digital converter 4, a comparator 8 for comparing the counted value and the reference value of the counter 6, To control the input / output of the microcomputer 10. Is composed of input and output control unit (7).

The microwave food monitoring method and effect of the present invention for detecting food weight with a microcomputer will be described in detail with reference to FIG. 7, which is a signal flow chart for detecting microwave food weight of the present invention.

When the user puts the food to be automatically thawed in the microwave and operates the auto thawing key, the mechanical operation of the food weight sensing unit, the weight sensor, and the amplification unit operate in the same configuration as in the prior art.

When the auto thaw key is applied and the auto thaw signal is applied to the microwave oven, the main relay (mair reluy) is turned on to rotate the glass tray 11 of FIG. 2 and to turn on the lamp in the refrigerator. Due to this, the roller 12 rotates along the rotational trajectory of the glass tray 11 to apply weight to the sensor 1, and the sensor 1 outputs a voltage induced by the weight to the amplifier 2 of FIG. 1. The microcomputer 10 resets the amplifier 2 to clear the output of the sensor 1 in the initial state. Thereafter, the amplifier 2 amplifies and latches the weight sensing signal of the sensor 1 to a predetermined level and applies it to the microcomputer 10.

In this case, the microwave food weight sensing method of the present invention, which is an operation process of the microcomputer 10, will be described below.

After converting the weight sensing signal of the sensor 1 applied from the amplifying unit 2 into a digital signal at a predetermined cycle and storing it, and after a predetermined time, the roller 12 counts the number of times the sensor 1 is pressed. It is determined whether the counting value is "1". At this time, if the counting value is "1", since the roller 12 pushes the sensor 1 in the initial state, the output value of the sensor 1 is discarded without being accumulated and the reset unit 3 is operated to reset the roller. If the counter value, in which the number of times the sensor 12 presses the sensor 1, is not "1", the maximum value and the minimum value of the output value of the sensor 1 are sorted and stored, and are integrated. Integrate the number of times you pressed.

After that, by determining the total number of times, the counter value of the total number of times is cleared and the food weight value, which is the output value of the sensor 1, when the number of times of the deviation is set to a multiple of the eccentric data period (for example, 3 times), for example, 6 times. The maximum value and the minimum value are set, and the deviation is calculated and integrated. When the number of times of integration of the counter 12, which is the number of times the roller 12 presses the piercing sensor 1, is 13 times, the sensor is twice the deviation period (6 times). Find the deviation between the maximum value and the minimum value of 1), divide it by 2, which is a multiple of the deviation period (6 times), and find the average deviation. Compare the eccentric load reference value with the average deviation greater than the eccentric load reference value. After the eccentric flag is set, the sensor 1 is reset and the above process is repeated. If the reference value of the eccentric load is large, the sensor 1 is recognized as a normal state and the above process is repeated.

On the other hand, in the integration count determination process, if the integration count is not 17, the sensor reset step is repeated. If the integration count is the final factor, the piezo sensor (1) output integration value is integrated into the sensor 12. The average value of the sensor is stored by dividing the number of times of pressing, and when the average value of the sensor is smaller than the weight of the glass tray 11 or greater than the maximum weight, the output of the sensor 1 is compared with the average value of the sensor and the weight of the glass tray 11. Reset and process it as an error state, otherwise judge it as an eccentric fragment state and if it is set, apply the correction value (1- (eccentric deviation x weight deviation weight) to the average pack of the piezo sensor 1 that it is an eccentric load state. After multiplying and storing as an average value, it is converted into an automatic thawing time corresponding to the average value.If the eccentric flag is not set, it is recognized as a normal state rather than an eccentric load and the average value of the sensor is recognized. Auto defrost function is performed by converting to self-thawing time.

As described in detail above, in the microwave food weight sensing method of the present invention, when food is placed in a glass tray, the food weight is determined to be an eccentric state and a normal state with the weight of the food. Compensation for the weight of the food accurately detects the effect of improving the microwave oven.

Claims (7)

If the food is placed on the glass tray of the microwave oven, determining the operation status of the weight sensor, storing the value of the sensor digitally, counting the number of detections, and resetting the sensor if the sensor number is "1". Otherwise, after storing and integrating the maximum and minimum values of the sensor, determining the number of sensor detections, calculating the deviation of the sensor output if the number of sensor detections is in the deviation cycle, and eccentric load if the sensor detections are twice the deviation cycle. An eccentric load determination step of determining the error, a step of storing the average value of the sensor if the number of sensor detections is the final number, an error determination step of determining an error by the average value of the sensor, an eccentric load determination step of determining an eccentric load after the error determination, and , Compensation step of compensating and storing as sensor value in case of eccentric load, and auto thawing function by changing sensor value to auto thawing time. Microwave food weight detection method for detecting a step. The microwave food weight sensing method of claim 1, wherein the eccentric load determination step determines the eccentric load state when the sensor value is large and the normal state when the sensor value is larger than the output value of the sensor and the eccentric load reference value. The method of claim 1, wherein the deviation cycle state is set as a multiple of the sensor data output cycle. The microwave food weight sensing method of claim 1, wherein the error determination system determines an error if the sensor average value is less than the glass tray weight. The method according to claim 1, wherein the error determining step determines that the sensor average value is an error if the sensor average value is larger than the maximum glass tray weight. The method of claim 1, wherein the compensating step is to compensate by multiplying the average value of the sensor by a compensation equation. 7. The method according to claim 6, wherein the compensation equation compensates with a free number of 1 for the product of the mean deviation and the weight weight.