JPS58181288A - High frequency heater - 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 The present invention relates to a high-frequency heating device that automates cooking by combining a microcomputer and various processors.

With the development and cheaper prices of microcomputers and the development of various sensors, microwave ovens capable of automatic cooking have appeared and are now in the spotlight.

It has also been proposed to use a plurality of processors to expand the cooking menu and to provide multiple functions.

Among them, humidity sensors used in microwave ovens that automatically cook food by detecting steam from food have stable characteristics that make them less likely to react to impurities such as seasonings and alcohol other than water vapor compared to other gas sensors. . The purpose of the present invention is to take advantage of the features of this humidity sensor, and even when used in combination with other sensors, to more efficiently combine it with a microcomputer to automate many food and cooking methods. shall be.

There are various unique patterns of steam generation obtained when food is heated, depending on the type, size, initial temperature, etc. of the food. Foods containing a lot of moisture generate a large amount of steam, while dry foods such as bread and bread produce less steam. In addition, when defrosting frozen foods, the amount of steam must be detected before the food becomes boiled, so the amount of steam is extremely small. Detects the minimum humidity after that, and when a predetermined amount of increase in humidity is reached according to the food and cooking method with respect to this value,
The steam detection microcomputer (hereinafter abbreviated as microcomputer) recognizes the steam and automatically cooks with each heating pattern based on the time required. Since the microcomputer operates digitally, it cannot read the signal from the humidity sensor as it is, but must perform analog/digital conversion (hereinafter abbreviated as A/D conversion). The resolution of this A/D conversion is determined by the number of output terminals of the microcomputer used; for example, if 5 pins are used, it will be 25-32 steps, and if 6 bits are used, it will be 2-64 steps. The number of outputs and operating speed of a microcomputer are unique to each microcomputer, and there are limits to these from technical and cost perspectives. Also, if the operating speed of the microcontroller is constant, A
There is an inversely proportional relationship between the conversion speed and resolution of /D conversion, and if either one is prioritized, it will be impossible to match the steam generation patterns of many foods and cooking methods. Therefore, in the present invention, depending on the type of food and cooking method,
By changing the number of bits used for A/D conversion of the microcontroller,
It is possible to provide an easy-to-use automatic microwave oven that automates more cooking menus.

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

FIG. 1 is an external view of a high-frequency heating device showing an embodiment of the present invention. It has an exhaust port 3 for discharging wind, food vapor, etc.

FIG. 2 shows a front view of the operation unit 1. When no cooking program is set, the time is always displayed on the display unit 4, and the clock switch 6 and the clock switch 6 are used to set the time display. , can be input using the numeric keys 6.

In normal manual cooking, after selecting high frequency output using the power key 7, an arbitrary time is input using the numeric keys 6, and cooking is started using the start key 8. Keys 9 and 10 are an automatic cooking key controlled by a humidity sensor and an automatic defrosting key. By tapping these keys, a number 1 corresponding to the type of food will appear on the display 4, such as A3.
is displayed, and by pressing the start key 8, cooking or defrosting can be performed automatically. 1
The cancel key shown in 1 is used to temporarily stop cooking,
Or a key used to cancel a program.

FIG. 3 shows a cutaway plan view of the high-frequency heating device shown in FIG. The food (not shown) enters the refrigerator and passes through the exhaust port 15 along with the steam. The exhaust gas that passes through the humidity sensor 16 and is installed on the top plate of the body! It is discharged from air port 3. 17/l'r
, humidity sensor 166, +, -'.

FIG. 4 shows the humidity sensor 16, which is composed of a humidity detection element 16-a and a cleaning heater 16-b. The cleaning heaters 16-b serve to heat the surface of the humidity detection element 16-a to about 500° C., burn off dirt adhering to the surface, and maintain stable humidity characteristics. FIG. 6 shows an outline of the circuit diagram inside the operation unit 1, in which the completion bits (R9-R15) of the output of the microcomputer are supplied to the reference voltage generator 20, where the inverter and resistor matrix are used to Generate a reference voltage at point A. The signal voltages divided by the humidity sensor 16 and the resistor 21 are compared by the comparator 22, and read into the input 2 at the timing of R1 via the transistor 23 and the resistor 24. With this signal, the outputs of R9-R15 are finally changed, and A
The reference voltage at the point is brought closer to the signal voltage of the humidity sensor 16, and when the reference voltage and the signal voltage intersect, the microcomputer 19 recognizes the level of the signal voltage. This is an A/D converter. There are several ways to bring the reference voltage closer to the signal voltage. Among the input cuff bits, the one with the heavier weighting, that is, the one a of the reference voltage generator 20, is sequentially output, and the signal voltage is determined by trial and error. means to find
Alternatively, the microcomputer 19 has the ability to process signals simultaneously by raising or lowering the voltage one step at a time from either the maximum voltage or the minimum voltage.
Since it is only a bit, the display on the display tube 4 and the manual key 5
The reading of ~11 is processed in a time-division manner, and one round is called one scan, which takes about 10 m5 ec.

Since one scan is required to change the reference voltage at point A once, the former method requires 7 scans since it is a complete bit, and the latter method requires 27-128 scans, 1.2
It takes 8 seconds.

In addition, in a microwave oven in which other sensors such as the temperature probe 26 that can be inserted into food to detect its internal temperature can be used, the circuit configuration thereof is exactly the same as that of the humidity sensor 16, as shown in FIG. However, since the microcomputer 19 alternately checks the humidity sensor 16 and the temperature probe 25, the time required for A/D conversion is twice as long as the above-mentioned time. Comparing the former means and the latter means, the former is extremely advantageous in terms of A/D conversion speed, but has the disadvantage of being susceptible to noise. If the output of the comparator 22 is inverted due to noise when a heavily weighted input among the 7 binoto inputs is compared with the signal, if the input is, for example, b, its weight will be 25-32. , resulting in an error of 32 levels. In the latter method, the change is made in units of levels, and the error due to noise is at most levels, so for microwave ovens that have components that are likely to generate noise, such as the magnetron 13, the latter is adopted from the perspective of preventing malfunctions. It is advantageous to do so.

While the operating speed of the microcomputer 19 and the A/D conversion method are fixed in this way, in the present invention, the number of output nodes of the microcomputer 19 used for A/D conversion is changed, and the humidity sensor 16. Alternatively, the speed or resolution of A/D conversion is made to correspond to the detection status of signals from other sensors 25. That is, the low-weighted q output of the reference voltage generator 20, 9.
The A/D conversion speed is increased by setting 4 levels or 32 levels.

When the humidity detection element 16-a is heated to 150° C. or higher, it exhibits a thermistor characteristic, which can be used to control the cleaning temperature. Cleaning heater 16
-b is provided near the pole of the humidity detection element 16-a, so the temperature rise during cleaning is steep. In this case, the A/D conversion is set to 5 bits to increase the conversion speed. The cleaning temperature must be controlled to prevent deterioration of the humidity detection element 16-a and the cleaning heater 16-b due to overshoot.

Additionally, when thawing frozen food, vapor detection must be performed before the food becomes "boiled".
The amount of change in relative humidity is only 2-3%. In order to successfully detect this, it is necessary to use 7 bits for A/D conversion and 12
Humidity detection may be performed at 3 to 4 levels with 8 levels and a sensitivity of about 0.8% RH per rubel. what if,
A/D change 1o/.

If you use 6 bits instead, the sensitivity per level is 3%.
RH, which not only makes it impossible to detect a change in humidity of 2 to 3% RH, but also requires rubel detection, so it is obvious that there is a risk of malfunction due to noise.

When cooking meat and vegetables, the amount of change in humidity is 10 to 2.
It is sufficient to detect a change in 0%RH, and A/D conversion uses 6 bits, which is intermediate in speed and resolution.
Appropriate humidity detection time can be obtained. Further, in a microwave oven using a temperature globe 25 or the like, the speed and resolution of A/D conversion may be arbitrarily selected depending on the operating temperature range.

As described above, according to the present invention, sensors and microcomputers can be efficiently combined, more foods and cooking methods can be automated, and an easy-to-use microwave oven can be provided. be.

[Brief explanation of the drawing]

Fig. 1 is an external perspective view of a high-frequency heating device showing an embodiment of the present invention, Fig. 2 is a dry side view of the operating section of the same, Fig. 3 is a partially cutaway plan view of the same, and Fig. 4 is a diagram of the same device. External perspective view of humidity sensor,
FIG. 5 is a control circuit diagram of the device. 1...---Operation unit, 2...Door, 3...---
・-・Exhaust port, 4...Display tube, 12...
・Cooling fan, 13 magnetron, 16...-humidity sensor, 19... microcomputer, 2o...
・・・・Reference voltage generator 0 Name of agent Patent attorney Toshio Nakao and 1 other person 1) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A heating chamber for storing food, a high frequency oscillator for supplying high frequency power into the heating chamber, and a microcomputer for controlling the high frequency oscillator? a side leg circuit including a side leg circuit, an intake section and an exhaust section that take in and exhaust air into the heating chamber, and a humidity sensor located near the exhaust section that detects water vapor from the food;
an amplifier that converts a change in resistance value of the humidity sensor into a change in voltage; a reference voltage generator that generates a reference voltage according to a signal from the microcomputer;
and a comparator for comparing the output voltage of the reference voltage generator with the output voltage of the reference voltage generator. A high-frequency heating device with a configuration that allows the resolution or response speed to be changed.