JPS5895123A - Automatic heating apparatus provided with sensor - Google Patents

Abstract

PURPOSE:To ensure a stable automatic heating by a construction wherein the temperature in a heating chamber is detected and the reference value with which the amount detected by a gas sensor is compared is made varibale in accordance with the detected temperature. CONSTITUTION:A thermistor 13 is provided to measure the temperature in a heating chamber 6 and input the value to a control unit 9. This measurement is made at least at either when heating commences or when steam commences to generate. The control unit 9 is adapted, when receiving the detected temperature as an input, to reset a threshold value alpha corresponding to the temperature in the system. Thus, the total heating time can be set at a stable value regardless of the temperature, and a sufficient allowance between the threshold value alpha at a high temperature and the total quantity of variation can be obtained, and therefore sensor 10 can be prevented from becoming insensitive. Further, the temperature at which the sensor 10 or a detection circuit becomes inoperative is set as a hot level, and when the thermistor 13 detects the hot level, the heating is interrupted and an alarm is sounded by a speaker 14. By this arrangement, a stable automatic heating can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control method for an automatic heating device equipped with a senna.

In recent years, significant advances in semiconductor technology have resulted in higher functionality of control circuits,
Successful miniaturization due to high integration and cost reduction due to mass production effects led to the use of these electronic control circuits in household electrical appliances.

Intelligence based on electronic control has rapidly progressed in various heating devices such as electric ovens, electric ovens, microwave ovens, gas ovens, and combination products of these. A particularly notable trend in heating devices is that automatic heating devices, which detect the heating state of objects to be heated using various sensors and automatically control heating, have quickly become popular.

This system uses a sensor to automatically terminate heating without the user having to manually set the heating time, output, heating temperature, etc., as in the case of conventional methods. Microwave ovens and other devices that require consideration of temperature and other factors have become much easier to operate and can now perform force μ heating with fewer failures.

As such prior art, Japanese Patent Application Laid-Open No. 61-13495
There is No. 1. This detects the change in humidity generated from the object to be heated, and determines the point at which steam is generated when it reaches a certain set value. The total heating time is the sum of the heating time T1 to reach that point and the product RT1 of a separately determined coefficient R specific to the heated object.

This is an example of automatic heating control using a so-called humidity sensor, but it is also an extremely effective control method for a so-called gas sensor that reacts with steam, alcohol, and carbon dioxide. However, this method also had the following drawbacks. In other words, when the temperature inside the heating chamber becomes high, the relative humidity decreases and the state becomes dry, so the detection level of humidity sensors and gas sensors that react to steam decreases, and even if steam starts to come out from the heated object, the detection level will decrease. , it was difficult to obtain sufficient sensitivity compared to when the temperature was low.

FIG. 3 is an example clearly showing such a situation. First, [1] when heating is started when the inside of the heating chamber is at room temperature will be explained. At the beginning of heating, the temperature inside the heating chamber gradually increases due to the heating source, so the relative humidity inside the heating chamber decreases. However, as the temperature of the heated object rises and the generation of steam becomes active ('P 1 point)
1. Overcoming the decrease in relative humidity caused by the rise in temperature in the heating chamber, the relative humidity begins to show an upward trend. Then, the point P when the humidity exceeds the threshold α where the humidity tends to increase
2 is the steam generation point, and the heating time T until reaching that point is
According to JP-A-51-13, the total heating time is defined as the product RT1 of 1 and a coefficient R unique to the heated object, which is added separately.
This is the idea of No. 4951.

However, when heating is started when the temperature inside the heating chamber exceeds es o 'Ck ((2)), the relative humidity has decreased considerably from the beginning of heating, that is, it is in an extremely dry state, [1] Even if exactly the same amount of water vapor is generated from the heated object, the relative humidity will not change as much as [1].

According to the humidity curve, when the room temperature is 20℃ and the relative humidity is 40℃,
If the temperature inside the heating chamber rises to 50'C, the relative humidity inside the heating chamber decreases to 10% at this time. It is assumed that water vapor of IQg is generated from the object to be heated in this state.

At this time, if the inside of the heating chamber is 20"C, which is the same as the room temperature, the relative humidity will reach 100", or reach the saturated state, but 5
If the temperature rises to 0'C, it will only reach 20%. At point p(1), the relative humidity has changed by 6 degrees, but at point [2], it has changed by only 10%.Therefore, when steam generation point P2'e is detected at a certain threshold value α, it is compared to point 22. Therefore, the heating time T1 becomes too long, leading to overheating.

The margin for the total amount of change with respect to the threshold value α is also small, and the sensitivity is no longer maintained and the risk of failure is high.

In view of this background, the present invention provides a sensor control system that realizes stable and reliable automatic heating independent of the temperature inside the heating chamber.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of the main body of the automatic heating device according to the present invention. A door body 2 is attached to the front surface of the main body 1 so as to be openable and closable, and an operation panel 3 is arranged. On the operation panel 3, there are provided at least a keyboard 4 for selecting a heating sequence depending on the object to be heated, and a display section 5 for making various notifications.

FIG. 2 shows a control block diagram of such a heating device. A heated object 7 is placed in the heating chamber 6, and a magnetron 8 is connected as a heating source. The magnetron 8 is the control unit 9
The power supply is controlled by

The detailed configuration of the control section 9 will be described later. 10 is a humidity sensor or a gas sensor, and water vapor from the heated object 7 is exhausted by a fan 11.

Gas 12 such as alcohol and carbon dioxide gas is detected.

13 is a temperature detection means such as a thermistor, which measures the temperature inside the heating chamber. Based on the detection data, the control unit 9
It controls the power supply to the magnetron 8, displays various data on the display section 6, and issues various notifications and warnings through a speaker or a buzzer 14 with synthesized voice or buzzer sound.

Now, how the control section 9 operates with this configuration will be described. Figure 3 has already been described.

The point is that even if the same amount of water vapor is generated from the same heated object, the amount of change in relative humidity will vary greatly depending on the temperature inside the heating chamber at that time. The present invention stably and reliably determines the point of steam generation by monitoring the temperature inside the heating chamber, and realizes automatic heating using a sensor that does not depend on the temperature inside the heating chamber.

FIG. 4 is a graph showing the steam generation point detection method according to the present invention. The control unit 9 first measures the temperature inside the heating chamber using the thermistor 13. It goes without saying that accurate control can be achieved by performing such measurements throughout the entire heating time, but the purpose of the present invention can also be achieved by measuring at least at the start of heating, at 21 points, or at any one of the 22 steam generation points. .

Based on the temperature thus measured, the control section 9 presets a threshold value α corresponding to the temperature in the system. That is, in the case of [1], α1 is preset, and in the case of [2], where the temperature is higher than n, a smaller threshold value α2 is preset. This results in vapor detection points P2 and P2
'You can match the points. Therefore, the total heating time can be determined stably regardless of the temperature. In addition, there is a sufficient margin between the threshold value and the total amount of carbonization at high temperatures, and the sensation of sensitization can be prevented.

Note that this example shows a configuration in which the total heating time can be determined stably based on the amount of the object to be heated, regardless of the temperature inside the heating chamber, but in reality, if the temperature inside the heating chamber is measured, the object to be heated is Thermal energy is also supplied from the ambient temperature.

Therefore, the total heating time may be slightly shorter. This can be achieved by setting α2 smaller. Since the trench steam generation point P2' is set even earlier than in FIG. 4, the T1 time can be shortened, and the total heating time can therefore be shortened.

Furthermore, when the temperature inside the heating chamber becomes high, for example, in a hybrid heating device that uses electric heaters and microwaves, such as a so-called open range, the temperature inside the heating chamber immediately after using the heater is 260℃.
Although the temperature reaches up to ~300°C, the threshold value α becomes an extremely small value in such a state. Therefore, if noise is introduced into the sensor or its detection circuit, false detection is likely to occur. Therefore, in the present invention, the temperature at which the sensor or its detection circuit becomes disabled is defined as the hot level, and if the hot level is detected during temperature measurement by the thermistor, heating will not start, or if heating is in progress, the heating source will not be turned on. Equipped with a safety circuit that stops power supply and interrupts heating. The user is informed of the failure of the sensor by displaying on the display means or by making a synthesized voice notification from the speaker 14 by the voice synthesizing means.

FIG. 6 shows the voltage waveform actually detected by the sensor, where (&) represents the humidity sensor and (b) represents the gas sensor. The relative humidity detected by the humidity sensor shows the same changes as described in FIG. 4, and there is nothing to add. Regarding the gas sensor, this graph is a direct reading of the change in impedance of the sensor, and it can be seen that the change in relative humidity becomes smaller as the temperature rises, so the change -1 in the detected value becomes smaller. Therefore, if the threshold value α is controlled according to the temperature of the heating chamber as in the present invention, good automatic heating can be realized.

Note that the threshold value α may be an absolute value as in this embodiment, or may be a relative value such as the voltage ratio of the 21st point and the 22nd point.

Now, how to realize the above control method and the specific configuration of the control section will be described in detail below.

FIG. 6 is a block diagram showing the functional configuration of the control section 9. As shown in FIG. The analog quantity detected by the sensor 10 is converted into a digital quantity by the hum/D converter 15 t'L, V+
The signal is input to a detector 16 and a level comparator 17. The v1 detector 16 is a block that detects levels at 21 points, and detects the minimum value in the case of a humidity sensor and the maximum value in the case of a gas sensor, and transfers them to the v1 holding register 18. Specifically, the V11J output device 16 first reads the value of the v1 holding register 18, compares it with new data, and updates the v1 value to the v1 holding register 18.

On the other hand, the thermistor 13 measures the temperature inside the heating chamber and
D converter 19 can be converted to analog quantity by one person. Mu/
The D converter 19 converts this into a digital quantity TMP,
The corresponding threshold value αn is read out from the α register 21 by the α selector 2o and inputted to the level comparator 17. The system/D converter 19 also has a function of detecting the sensor performance level and outputs a HOT signal.

The saturation level comparator 17 compares the sensor information inputted from the MU/D converter with the above-mentioned v1 value, and determines whether or not it exceeds a predetermined threshold value αn inputted from the α selector 2o. In other words, 22 points are detected. 22
When the point is reached, a HOT signal is output.

When the HOT signal is output, the up counter 22 stops counting the clocks. Then, the T1 time counted by the up counter 22 is input to the multiplier 23,
Additional heat time Rm-T+ is calculated and down counter 2
It is preset to 4.

For the constant Rm, a value corresponding to the menu selected by the keyboard 4 is read from the R register 26 by the R selector 25 and input to the multiplier 23.

On the other hand, power supply to the magnetron 8 is started by the flip-flop 27 immediately after the start key is pressed. 28 is a drive circuit that operates the magnetron 8.

Flip-flop 27 transitions to additional heat mode, and decoder 29 detects that the content of down counter 24 has become zero.
From the point detected by , that is, 22 points, Rm@T
When one hour has elapsed, the heating is terminated by being reset by the ZERO signal. The flip-flop 27 is also reset when the HOT signal is output by the memory/D converter 19, that is, when the heating temperature exceeds the sensor level, and the heating is prohibited or interrupted.

The HOT signal is also input to the display section 6 and the synthesizer 30, which is a voice synthesis means, and a warning is given to the user in the form of a display and synthesized voice.

As described above, the present invention can be realized by the control section shown in FIG. It goes without saying that each of the functional blocks shown in FIG. 6 can be replaced with soft logic based on a program, and most of them can be realized by an aerosic controller such as a microcomputer.

As explained above, according to the present invention, stable and reliable automatic heating of the sensor can be realized without depending on the temperature inside the heating chamber. Furthermore, even at high temperatures, a sufficient margin can be maintained between the threshold value and the total amount of change, and the sensation of sensitization can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the main body of the automatic heating device according to the present invention, Fig. 2 is a block diagram of the same, and Fig. 3 shows changes in relative humidity in the heating chamber, schematically illustrating the conventional control method. Figure 4 is a diagram showing the control method according to the present invention, and Figure 6 is a diagram showing quantities measured by actual sensors, (a) shows a humidity sensor, and (b) shows a gas sensor. Each is shown. FIG. 6 is a functional block diagram of the control section. 6... Heating chamber, 7... Heated object, 8.
...Magnetron, 9...Control section, 10
...Sensor, 13...Thermistor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] (1) A heating chamber in which the object to be heated is placed, a heating source coupled to this heating chamber, a control unit that controls the power supply to the potash heat source, and water vapor, alcohol, and carbon dioxide gas emitted by the object to be heated. a sensor that detects the temperature of the heating chamber, a temperature detection means that measures the temperature of the heating chamber, and a comparison means that compares the amount detected by the sensor with a predetermined value, and the control section is directly controlled by the temperature detection means. Alternatively, an automatic heating device includes a sensor that changes a predetermined value serving as a reference for the comparison section according to the indirectly measured temperature of the heating chamber. Shun) The sensor according to claim 1, wherein when the temperature detection means measures that the temperature of the heating chamber is high, the control section changes the predetermined value serving as a reference for the comparison section to a smaller value. Automatic heating device with. 3) Using the temperature detection means, the control section classifies the temperature of the heating chamber into at least three levels, sets the highest level threshold value to substantially match the level at which the sensor becomes disabled, and controls the temperature when the temperature level is detected. According to claim 1, the control unit prohibits or interrupts power supply to the heating source.
Automatic heating device equipped with the sensor described in Section 2. 4) An automatic heating device equipped with a sensor according to claim 3, further comprising a display means or a voice synthesis means for notifying the inability of the sensor.