JPH0517458B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a heat cooker with a weight detection function that improves cooking performance by measuring the weight of food and cooking the food according to the weight. be.

Structure of conventional example and its problems An example of a conventional heat cooker with a weight detection function is a high-frequency heating device disclosed in Japanese Patent Application Laid-open No. 160742/1983. This high-frequency heating device uses a spring to support a food placing table, vibrates it using the elasticity of the spring, and measures the weight of the food by detecting the vibration frequency. It is true that heating can be done according to the amount of food, so there is no need for the user to set the heating time or heating output, and there is an advantage that cooking performance is improved.

However, in reality, the elastic constants of springs vary when they are mass-produced, which causes errors. Furthermore, when mass-produced, the weight of the mounting table itself varies, making it impossible to accurately measure the weight of the food. If the weight of food cannot be measured accurately, heating control will be disrupted and the food will be undercooked.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and aims to accurately detect the weight of food with a simple configuration and enable stable heating and cooking.

Structure of the Invention In order to achieve the above object, the heat cooker with a weight detection function of the present invention includes a weight reference point adjustment setting means to correct an error in the reference weight, and a set value of the weight reference point adjustment and setting means. This corrects the detected weight. This weight reference point adjustment setting means is independent of the weight detection means, and is configured to correct the value detected by the weight detection means with the setting value of the weight reference point adjustment setting means, so that accurate food detection can be achieved. Weight can be measured. Furthermore, since the weight detection means and the weight reference point adjustment and setting means are independent, the circuit structure is simple and the adjustment range can be easily widened.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an external perspective view of a microwave oven which is a high frequency heating device as an embodiment of the present invention. Reference numeral 1 denotes a heating chamber, and a door 2 that can be freely opened and closed is provided on the front side of the heating chamber, and 5 is a main body that covers the main body. A display section 3 for displaying heating temperature, heating time, weight of food, etc. is provided on the front surface. The display section 3 further displays the detected weight of the weight detecting means or a value corresponding to the detected weight, the set value of the weight reference point adjustment setting means, etc. during setting of the reference weight. 4 sets the heating time, heating output, cooking menu,
An operation input section is provided for instructing to start or stop cooking.

FIG. 2 shows a side sectional view showing the structure of this microwave oven. In the figure, a heating chamber 1 that stores food 6
A door 2 that can be opened and closed for taking food in and out is provided on the front side of the door 2. The structure is such that a tray 7 for receiving food 6 is provided and placed on a stand 8. The mounting table 8 is supported by a mounting table shaft 10 passing through a hole in the bottom plate of the heating chamber, and is held by being inserted into the shaft 11. The shaft 11 is rotatably fixed by a vibration-side spring spacer 16 and a shaft fixing member 19. Therefore, the loads of the food 6, the tray 7, the mounting table 8, etc. are applied to the vibration-side spring spacer 16. The vibration side spring spacer portion 16 is supported by the plate spring 12 and connected to the fixed side spring spacer 17. This plate spring 12 is attached in parallel via a vibration side spring spacer 16 and a fixed side spring spacer 17, and is pressed and fixed by a fixed side spring body 18, a bearing 20, and a shaft fixing member 19. A motor 15 for rotationally driving the mounting table 8 is attached to the vibration-side spring spacer of the vibration section, and a rotational driving force is applied to the shaft 11 via the motor-side gear 14 and the shaft-side gear 13.
is being communicated to. Fixed side spring spacer 1
7 and the fixed side spring body 18 are fixed to the spring mounting base 9.

With the above configuration, the weight of the vibrating parts such as the food 6 and the mounting table 8 is applied to the leaf spring 12. This frequency is determined by the load applied to the leaf spring 12 and the elastic constant of the leaf spring 12, and if the same leaf springs 12 are used, the frequency corresponds to the load. If the load is large, the frequency will be small; if the load is small, the frequency will be large. A magnet 21 is used to detect this frequency.
and a detection coil 22 are provided. Magnet 2 in the vibrating part
1 and fix the detection coil 22 in a vibration-free place. In this configuration, the magnet 21 vibrates together with the vibrating section, thereby changing the magnetic field strength in the non-vibrating sensing coil 22, thereby generating an electromotive force in the sensing coil 22. This detection coil 2
The frequency of the electromotive force generated in the magnet 21 is the vibration of the magnet 21, that is, the vibration itself. Therefore, by detecting the frequency of the electromotive force generated by the detection coil 22, the load applied to the leaf spring 12 can be detected. Therefore, it is necessary to generate vibrations in this vibrating section. Therefore, an excitation arm 23 is provided to apply vibration to the vibrating section. Also, this vibration arm 2
3 is configured to operate in conjunction with the opening/closing operation of the door 2. This configuration is shown in FIG.

FIG. 3 is a perspective view of a vibrating section constituted by the leaf spring 12 and an excitation mechanism section for generating vibration in the vibrating section. First, the door 2 is in a state where it can be opened and closed freely, and the door arm 25 is connected to the door 2.
The door arm 25 transmits the opening/closing operation of the door 2 to the excitation cam 26. This excitation cam 26 rotates by a predetermined angle. and excitation cam 26
is provided with a small diameter part and a large diameter part, and the excitation lever 27 is in contact with either the small diameter part or the large diameter part,
The rotation of the excitation cam 26 moves the small diameter portion and the large diameter portion. An enlarged view of the excitation cam 26 is shown in b. Excitation levers 27 for the small diameter part and the large diameter part of the excitation cam 26
The contact trajectories are shown by dotted lines in the order of A to D. When the door 2 is closed, the excitation lever 27 is at point A, and as the door 2 is opened, it moves to point B.
It moves from the small diameter part to the large diameter part at point C, and as the door 2 is further opened, it reaches point C. That is, the excitation lever 27 moves from the narrow diameter portion to the large diameter portion by opening the door 2. Conversely, for the action of closing door 2, the movement goes from point C to point D. Since the trajectory at this time is being pulled by the coil spring 39, it passes through point D and reaches point E. Then, at point E, the cam pushes it toward the narrow diameter portion and returns to point A. That is, by closing the door 2, the excitation lever 27 moves from the large diameter portion to the small diameter portion. The movement is rapid from point E to point A. With the above configuration, the angle of the excitation lever 27 changes by the difference between the small diameter part and the large diameter part in conjunction with the door opening/closing operation. This change is then transmitted to the excitation arm 23 by the excitation rod 28. The excitation arm 23 applies force to the vibrating section to generate vibration.

FIG. 4 shows a detection circuit for detecting the frequency of the vibrating section and a zero g adjustment circuit as a weight reference point adjustment and setting means for correcting the detected weight. First, when the magnet 21 attached to the vibrating section vibrates, an electromotive force having the same frequency as the vibration frequency of the magnet 21 is generated in the detection coil 22 . Since this electromotive force is small, it is amplified by an amplifier circuit 29, and a filter circuit 30 is provided to remove noise other than the vibration of the magnet 21. A waveform shaping circuit 31 is provided to shape the signal that has passed through the filter circuit 30 into a waveform that can be easily processed digitally by a microcomputer, that is, a square wave.
Then, it is input to the input terminal of the microcomputer 33. On the other hand, a zero g adjustment volume 32 is provided as a circuit for correcting the detected weight. The microcomputer 33 is configured to correct the detected weight detected by the detection circuit using a numerical value taken in by the zero g adjustment volume 32.

The data conversion method for inputting the zero g adjustment volume 32 to the microcomputer 33 is configured to include a zero g adjustment oscillator 38 that converts the resistance change of the zero g adjustment volume 32 into a frequency. Therefore, the oscillation frequency corresponding to the resistance value of the zero g adjustment volume 32 is input to the microcomputer 33.
The microcomputer 33 has a counter input terminal CT, and is configured to correct the detected weight based on this oscillation frequency.

FIG. 5 is a weight detection characteristic diagram showing the correction function of the detected weight by the zero g adjustment volume 32.
The horizontal axis is the period T, which is the reciprocal of the vibration frequency, and the vertical axis is the food 6
shows the weight W of. One of the causes of the measurement error included in the detected weight W of the food is the variation due to the elastic constant of the leaf spring 12, and the other is the variation in the initial weight, that is, the weight of the receiving tray 7 and the weight of the mounting table 8. There are variations in weight and other parts that make up the vibrating part. It is necessary to correct these. For example, B in the figure is based on a design with no variation, and there is no need to correct it at all. Therefore, the relational expression between the period T and the weight W of the food is stored in the microcomputer. The relational expression is a quadratic expression of W=C ₁ T ² +C ₂ T+C ₃ , which is the characteristic of B in the figure. For example, in the case of having the characteristic A in the figure, when the weight W of the food is 0 g, it shows a negative value. Therefore, it is necessary to correct the negative value of a-a'. Conversely, when the food has the characteristic C, it shows a positive value when the weight W of the food is 0 g. That is, it is necessary to correct the value of bb'.

FIG. 6 shows a reference point setting method using a zero g adjustment volume as a weight reference point adjustment and setting means. The reference point is when the tray 7 is placed on the eighth place and the weight W of the food is zero g. The weight at this time is important as a reference. The operation at this time will be explained according to the figure.
First, only the tray 7 is placed on the mounting table, and vibration is generated by the closing operation of the door 2. It vibrates at a frequency corresponding to the weight at this time, and the period T ₁ at that time is measured. At this time _T1 , the resolution is better if the period of a plurality of pulses (n pulses) is measured rather than the period of one cycle. Approximate formula W=C ₁ T ² + stored in the microcomputer 33 from the measured period T ₁
Calculate the measured weight by C ₂ T + C ₃ . Therefore, rather than correcting the reference point only once, it is better to measure it several times and then use the average to determine the correction value for the reference point. Therefore, in the case of FIG. 6, the method is to measure three times and take the average. Therefore, after the first weight W ₁ is taken in, the number display is changed. In other words, it is displayed that this is the second time. The display contents will be explained in detail later in FIG. 9. Perform the above operation three times. That is, W ₂ and W ₃ are taken in. Then, the average of the three measured weights W ₁ , W ₂ , and W ₃ is determined. Therefore, the zero g adjustment volume 32 is used to correct this.
It is necessary to match the set numerical value and the average value.
The zero g adjustment volume 32 is divided into 100 levels from 0 to 99 so that each level is equivalent to 3 g. The center value is then set to level 50. That is, the deviation from the center value is L=W/3 level. Also, since the 50th level is the center, Ld=
W/3+50 is the setting level of the zero g adjustment volume 32. The resistance value of the zero g adjustment volume 32 is converted into a frequency by the zero g adjustment oscillator 38, and is assigned from 0 to 99 according to this frequency. Therefore, set the resistance value of the zero g adjustment volume 32 so that it becomes the same value as the displayed Ld. This completes the weight reference point adjustment setting.

FIG. 7 explains the operation when measuring the weight W of actual food. First, the food 6 is placed on the tray 7 and the door 2 is closed to generate vibrations. Then, the period T of multiple pulses (n pulses) of the vibration at that time is measured. Approximate formula W = C ₁ T ² + C ₂ T stored in the microcomputer 33 from the measured period T
Calculate W′ by +C ₃ . It is necessary to correct this W′. Therefore, the set level is determined from the oscillation frequency determined by the resistance value of the zero g adjustment volume 32. Since each level is 3g and the center is assigned to the 50th level, the correction value is 3×(50−Ld). Therefore, the correct measured value W of the food 6 is W=W'+3(50-Ld). The measurement of food 6 is thus completed.

FIG. 8 shows a display section 3 and an operation input section 4 of a microwave oven as a heat cooker with a weight detection function according to the present invention.
FIG. And zero g adjustment volume 3
A printed circuit board 40 is shown on which electronic circuits such as 2 and a microcomputer 33 are attached and wired.

When the printed circuit board 40 is installed after the operation input section, it is installed so that the position of the zero g adjustment hole 34 and the position of the zero g adjustment volume 32 coincide with each other.
Then, the zero g adjustment volume 32 can be set by penetrating the zero g adjustment hole 34 with a screwdriver or the like. Further, the zero g adjustment hole 34 is not located on the front like the operation input section 4, but is located on the side in an inconspicuous location. This is because once the settings are made, they are rarely reset.

Fig. 9 shows the display contents when setting the weight reference point.
The operation at the time of setting has already been explained based on FIG. 6 above. FIG. 9a shows a state in which the microwave oven is normally stopped and the time is displayed. In order to switch from this state to the weight reference point setting mode, use the keys on the operation input section 4. This is done by not providing a special key for entering the weight reference point setting mode, but by inputting a plurality of predetermined keys in a predetermined order among the keys shown in FIG. 8. In other words, a setting method such as encryption may be provided. When the above weight reference point setting mode is input, a display as shown in FIG. In other words, “1
83" will be displayed. The 1 on the left side indicates the first measurement. The two digits 83 on the right indicate the setting level of the zero g adjustment volume 32. Then, the door 2 is closed and the first measurement is performed. When the measurement is completed, the display shown in Fig. 3c appears. That is, the left end changes from 1 to 2, indicating that the next measurement will be performed twice. Measurements are made in the same manner a second time and a third time. When the third measurement is completed, the value becomes "5283" as shown in e of the figure. The two digits on the left, "52", indicate the level of Ld explained in Figure 6. That is,
Since the center value was 52 levels compared to 50 levels, there was a two-level discrepancy. This needs to be corrected. Therefore, the level of zero g adjustment volume 32
It is set to match Ld. In other words, set the two digits on the right to be "52" so that they match the two digits on the left, "52." This completes the setting of the zero g adjustment volume 32. In this display, the left 2
Since you only need to set the digit and the two right digits to be the same value, it is easy to read and there are fewer chances of misreading.

FIG. 10 shows a control circuit diagram of a microwave oven which is an embodiment of the present invention. Microcomputer 33
plays a central role in the control section, and has memory, calculation, judgment, and input/output control functions, and performs the control shown in FIGS. 6, 7, and 9, and correspondingly controls the magnetron 24. It has a function of generating signal output for output control etc. 36 in the figure is an output control relay, which controls the output of the magnetron 24 based on a signal from the microcomputer 33. Reference numeral 37 denotes an operation control relay, which controls the operation of the microwave oven, such as cooking operations, stopping, and termination, based on signals from the microcomputer. 35 is a reference oscillation circuit for operating the microcomputer 33, and is also used for counting reference time.

In the above embodiment, the reference weight is 0 g when no food is placed on the tray, but the reference weight is not limited to this, and any weight may be selected as the reference weight.

As described above, according to this embodiment, a weight reference point adjusting and setting means is provided to correct the weight reference point, and the detected weight is corrected based on the set value of the weight reference point setting means. Furthermore, the weight reference point adjustment and setting means is constructed independently of the weight detection means. Therefore, the circuit configuration for correction is simple. Furthermore, since they are independent, the range that can be corrected can be widened.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) Since the weight reference point adjustment setting means and the weight detection means are independent, each circuit configuration can be configured exclusively according to the purpose, and can be realized with a simple configuration.

(2) Since the weight reference point adjustment and setting means and the weight detection means are independent, the adjustable range of the weight reference point adjustment and setting means can be freely changed, and a wide range of adjustment is possible.

(3) By configuring the weight reference point adjustment setting means with a volume, it can be realized at low cost.

[Brief explanation of the drawing]

Fig. 1 is an external perspective view of a microwave oven as an embodiment of the present invention, Fig. 2 is a side sectional view showing the structure of the microwave oven, and Fig. 3 is a vibrating part and excitation of a weight detection part that detects weight. A perspective view of the mechanical part, Figure 4 is a detection circuit diagram for detecting the frequency of the vibrating part, a zero g adjustment circuit diagram for correcting the detected weight, and Figure 5 is a correction of the detected weight using the zero g adjustment volume. Figure 6 is a flowchart showing how to set a reference point using a zero-g adjustment volume as a weight reference point adjustment setting means, and Figure 7 is a flowchart showing the operation when measuring the weight of actual food. , FIG. 8 is an enlarged perspective view of the display section and the operation input section, FIG. 9 is a diagram showing the display contents when setting the weight reference point, and FIG. 10 is a control circuit diagram of a microwave oven as an embodiment of the present invention. be. 1... Heating chamber, 2... Door, 3... Display tube, 4
...Operation input unit, 5...Main body, 6...Food, 7...Saucer, 8...Placement stand, 9...Spring mounting stand, 10...Placement table shaft, 11...Axis, 12...
Leaf spring, 13... Shaft side gear, 14... Motor side gear, 15... Motor, 16... Vibration side spring spacer, 17... Fixed side spring spacer, 18...
Fixed side spring fitting, 19...Shaft fixing material, 20...
Bearing, 21...Magnet, 22...Detection coil, 2
3... Excitation arm, 24... Magnetron, 25
... Door arm, 26 ... Excitation cam, 27 ... Excitation lever, 28 ... Excitation rod, 29 ... Amplification circuit, 30 ... Filter circuit, 31 ... Waveform shaping circuit, 32 ... Zero g adjustment volume , 33... Microcomputer, 34... Hole for zero g adjustment,
35... Reference oscillation circuit, 36... Output control relay, 37... Operation control relay, 38... Zero g adjustment oscillator, 39... Coil spring, 40... Printed circuit board, 41... Fan motor.

Claims (1)

[Scope of Claims] 1. A heating chamber for storing food, a heating source for heating the food, and a weight detection means for detecting the weight of the food by detecting the vibration frequency of an elastic body that supports the food. and a control section, and a weight reference point adjustment setting means that converts a change in resistance value of a volume that corrects an error in the reference weight into a change in oscillation frequency, and the control section is configured to adjust the set value of the weight reference point adjustment and setting means. The heat cooker with a weight detection function is configured to calculate the weight of the food based on the weight detected by the weight detection means, and control the heating output of the heating source based on the calculated weight. 2. The heat cooker with a weight detection function according to claim 1, wherein the weight reference point adjustment and setting means is constituted by a volume control. 3. The heat cooker with a weight detection function according to claim 2, characterized in that the resistance value of the volume is converted into an oscillation frequency.