JPH0268884A - High frequency heating device - 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 Field of Industrial Application The present invention relates to a heating device such as a microwave oven that is equipped with a weight sensor and configured to automatically control heating time.

BACKGROUND OF THE INVENTION Heating devices equipped with conventional technology sensors to automatically control the heating time are already in widespread use. For example, in microwave ovens, products that combine humidity sensors, gas sensors, and weight sensors have been commercialized.

The automatic high-frequency heating device described in Japanese Patent Application Laid-Open No. 58-240108 is an example equipped with such a composite sensor.

This automatic high-frequency heating device is equipped with a gas sensor that detects gas or steam generated from the object to be heated, and a weight sensor that detects the weight of the object to be heated.The former detects the completion of heating of the object. However, for the latter, the maximum heating time is calculated from the initial weight of the object to be heated before heating, and monitoring is performed to ensure that heating does not occur beyond this time.

In this way, heating is controlled in parallel based on the information obtained by the two sensors, so a small amount of the object to be heated, which is likely to be overheated if the heating is finished only by the gas sensor, is controlled by the maximum heating time by the weight sensor. Control stops heating early,
Improvements have been made in handling portion size throughout the shell.

It was also extremely safe even if the gas sensor broke or could not be detected for some reason.

Problems to be Solved by the Invention However, in the conventional automatic high-frequency heating apparatus as described above, the maximum heating time is calculated using a linear equation as shown in the following equation.

T, = AW, --- (1) where To: Maximum operating time A: Constant Wo: Weight of the object to be heated However, the actual optimum heating time for the object to be heated cannot be placed on the following equation. First, as shown in FIG. 1, the larger the amount, the more the equation deviates from this linear equation, and the optimum heating time tends to become somewhat shorter.

This is because when the heating device is a microwave oven, for example, the load characteristics of the magnetron, which is the heating means, changes depending on the amount of the object to be heated, and in general, the high frequency output is higher for a large amount of load than for a small amount of load, so it is heated more efficiently. This is thought to be due to the fact that the heating time is shorter than that of 4.

In atmospheric heating such as in an electric oven, the optimal heating time does not become longer in proportion to the quantity, but regardless of the microwave oven, the heating time slightly increases depending on the amount of the object to be heated. This is due to the time delay required for heat to be transferred to the center of the heated object and the slow rate at which the cold heated object lowers the temperature within the heating chamber.

In this way, the optimum heating time does not change linearly depending on the amount of the object to be heated. Therefore, although the conventional maximum operating time calculated using a linear formula works effectively for small quantities, it deviates from the optimum time for large quantities (and can no longer function as a finish sensor).

In view of this background, it is an object of the present invention to make it possible to effectively utilize the maximum operation time calculated based on the initial weight of the object to be heated, from a small amount to a large amount.

Means for Solving the Problems In order to solve the above problems, the present invention provides a heating chamber for heating an object to be heated, a heating means coupled to this heating chamber,
It is composed of a control section that controls the power supply to the heating means and has a calculation means, a mounting table on which the object to be heated is placed, and a weight detection means for detecting the weight of the object to be heated on the mounting table. .

Function: In the heating device of the present invention, the control section detects the weight of the object to be heated on the mounting table via the weight detection means, calculates the maximum heating time based on the measured value using the calculation means, The power supply to the heating means is controlled so that the maximum operating time obtained based on the calculation result is not exceeded under any circumstances.

With such a configuration and operation, the maximum operating time that can be used effectively from small to large quantities can be calculated based on the initial weight of the object to be heated.

EXAMPLE Hereinafter, a heating device according to the present invention will be explained with reference to the drawings.

FIG. 2 is a perspective view of the main body of a heating device such as a microwave oven according to the present invention.

A door body 2 is provided on the front surface of the main body 1 so as to be openable and closable, and an operation panel 3 is disposed thereon. Various heating command keys 4 are arranged on the operation panel 3. Among these, there are those that command automatic heating by exceeding the heating category or type of object to be heated, and those that command manual heating in which the user sets the heating time and heating output by himself/herself.

FIG. 3 is an embodiment of a block diagram showing the system configuration of the heating device according to the present invention.

Various heating commands inputted from the heating command key 4 on the operation panel 3 are decoded by the control unit 5 and a predetermined display is performed.

In the heating chamber 6, an object to be heated 8 is placed on a mounting table 7, and heated by a magnetron serving as a heating means 9. Power supply to the magnetron 9 is controlled by the control unit 5 via the driver 10.

In order to improve uneven heating of the object to be heated 8, the mounting table 7 is
It is rotationally driven by a drive source 11 during heating. At the tip of the drive shaft of the drive source 11 that freely moves in the thrust direction,
A weight detection means 12 is mechanically coupled.

As such a weight detection means, a strain gauge, a capacitance type pressure sensor, a displacement sensor, etc. can be used. 1
3 is a detection circuit.

Now, the control section 5 has a calculation means as described later,
The weight of the object to be heated is 1w as measured by the above-mentioned weight detection means.

Calculate the maximum operating time based on.

When an approximate equation was obtained from the optimum heating time of the actual object to be heated shown in FIG. 1, good agreement was found with a quadratic equation. Heating performance can be adjusted by setting 0.

To = a W6 z+ b We + c --
---(2) However, a, b, c: constants. Therefore, without combining a gas sensor and a weight sensor as in the conventional case, automatic heating can be performed sufficiently with only the maximum operating time of the weight sensor alone.

Also, when heating manually, it is useful to determine the maximum operating time based on the weight of the object to be heated, so that even if an abnormal heating time is set, there is no risk of a fire or other risk of the object to be heated. It can be prevented.

FIG. 4 shows an example of a specific circuit configuration of such a system. The control unit 5 is formed by a microcomputer, and the weight sensor 12 is a capacitive pressure sensor. An oscillation circuit is used as the detection circuit 13, and is formed by a combination of a sawtooth wave generation circuit and a waveform shaping circuit of an operational amplifier.

The output pulse of the oscillation circuit 13 is connected to the input terminal TC of the built-in counter of the microcomputer 5.

Reference numeral 22 denotes a level shift circuit for voltage conversion and waveform shaping, which may be added as appropriate.

For example, the operational amplifier is TLO82, and the microcontroller is MB88.
515, but it goes without saying that any device with equivalent functionality can also be used.

FIG. 5 is a flowchart showing a control program for such a microcomputer.

When weight measurement is started, a built-in counter connected to the TC terminal is activated (a), and measurement of output pulses is started.

The gate time of the counter, for example 1 second, is managed using a timer interrupt (b), and when this predetermined time has elapsed, the counter is stopped (c).

The counting result is transferred to a predetermined address in the RAM and stored (d).

After such processing, the count number stored in the RAM is
It is also converted to weight using a quadratic or cubic equation (e
).

W0 = A f ” + B f + C - - - - - (3) However, f: Number of counters A: Constant B: Constant C: Constant And based on this weight value, further calculate the maximum heating time (f). This is as already stated.

T, = aW, ” +bW, +c ----- (2) where a, b, c: constants Then power supply to the heating means is started (barrel, it is checked whether To has elapsed (5). If To Once the period has elapsed, the power supply to the heating means is unconditionally stopped (g).

If To has not elapsed, then it is checked whether automatic heating is being performed (i), and only in the case of manual heating, whether or not the set heating time has elapsed is monitored (j). If the set time has elapsed during manual operation, power supply to the heating means is stopped (g).

As described above, the heating device of the present invention can be used in various applications, from small quantities to large quantities.
A maximum operating time that closely matches the optimum heating time can be obtained, further increasing safety. Further, heating can be automatically ended using only the weight sensor without using a gas sensor and a weight sensor together as in the conventional case.

Furthermore, it will not operate for longer than the maximum operating time at any time, making it extremely safe even when abnormal settings are made.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a method of calculating the optimum heating time and maximum operating time for an actual object to be heated according to the present invention, FIG. 2 is a perspective view of the main body of a heating device such as a microwave oven according to the present invention, and FIG.
The figure shows a program showing the system configuration of the heating device according to the present invention, Figure 4 is a circuit diagram showing a specific example of the present invention, and Figure 5 shows the structure of the control program. FIG. 5-control unit, 6...-heating chamber, 7...-mounting table 8--object to be heated, 9...-heating means, 12...-weight detection means. Name of agent: Patent attorney Shigetaka Awano and one other person Figure 1 T. W. --- Maximum heating time --- Total weight of the object to be heated, c --- Constant number Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] a heating chamber that heats an object to be heated, a heating means coupled to the heating chamber, a control unit that controls power supply to the heating means and has a calculation means, and a mounting table on which the object to be heated is placed; The controller includes a weight detecting means for detecting the weight of the object to be heated on the mounting table, and the control section detects the weight of the object to be heated on the mounting table via the weight detecting means, and outputs the measured value. A heating device configured to calculate a maximum heating time using the calculation means based on the calculation result, and to control power supply to the heating means so that the maximum operation time obtained based on the calculation result is not exceeded under any circumstances. .