JPH0228052B2 - SENSATSUKI KANETSUCHORIKI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heating cooker equipped with a sensor.

Configuration of conventional examples and their problems In conventional sensor-added heat cookers, such as electronic ovens that use a thermistor, the temperature inside the oven is detected by the thermistor, and the control unit uses the detected temperature value to The temperature inside the oven is being controlled, but when the detected temperature value no longer shows the correct value due to noise etc., in order to prevent the control unit from controlling the temperature correctly, the control unit: A so-called multiple check (double check if twice) is provided in which the temperature detection value of the thermistor is deemed valid only when the temperature detection value matches a certain number of times or more. however,
This method is effective when the frequency and level of noise are small, but as the frequency and level of noise increases, the data becomes inconsistent due to the multiple checks and temperature control becomes impossible. . In other words, in an electronic oven, even if the temperature inside the oven actually becomes abnormally high due to the set temperature, the control unit cannot detect the temperature, so heating is not interrupted and the temperature inside the oven continues to rise. A problem arises.

Purpose of the Invention The present invention solves the above-mentioned drawbacks of the conventional technology, and aims to prevent a dangerous situation when valid data cannot be obtained due to noise etc. during multiple checks in temperature detection of a thermistor. purpose.

Structure of the Invention In order to achieve the above object, the sensor-added heat cooker of the present invention is configured to include a control section that stops heating if valid data cannot be obtained due to noise etc. in multiple checks. This can prevent dangerous situations such as flames.

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

FIG. 1 shows a side sectional view of an automatic heating cooker according to an embodiment of the present invention. 1 is a heating chamber in which the food to be heated 2 is placed; 3 is a high-frequency heating source connected within the heating chamber 1; The heating chamber 1 is provided with a sub-heating chamber 5 partitioned by a perforated plate 4, and the sub-heating chamber 5 is provided with an electric heating device 6 and a circulation fan 7 for circulating hot air into the heating chamber 1. 8 is a temperature sensor that detects the temperature inside the heating chamber.

In Fig. 2, when the start button 9 is pressed,
Oven cooking starts.

The control device 10 controls the temperature of the heating chamber 1 by means of a temperature sensor 8.
The temperature inside the heating chamber 1 is measured, and if the temperature inside the heating chamber 1 is lower than the control temperature, the heater relay 11 is turned on and power is supplied to the electric heating device 6. Also, if the control temperature is higher, the heater relay 11 will not turn on and the electric heating device 6 will turn on.
No power is supplied to.

FIG. 3 is an electrical circuit diagram of the present heating cooker. The voltage divided by the thermistor 8 and the fixed resistor 14 (hereinafter, this voltage will be referred to as thermistor data) is transmitted to the microcomputer 10 which is the control section.
is read and converted to temperature. Here, the microcomputer 10 reads the thermistor data at certain intervals, and only when this data matches a certain number of times or more consecutively, it considers the data to be valid, converts the temperature, and executes the temperature control described above.
As explained above, this is to prevent the thermistor data from being adversely affected by various noises such as power supply noise and static electricity noise, thereby preventing correct temperature control.

The above operation will be explained with reference to FIG. Figure 4a shows an example of the relationship between the resistor-divided voltage sensor voltage divided by the thermistor 8 and fixed resistor 14 in Figure 3 and time, and the black dots indicate the read timing by the voltage control unit. The number indicates a digital value (this is called thermistor data) when the control section A/D converts the sensor voltage. That is, the control section considers the thermistor data to be valid data only when it is the same data three times in a row, and performs temperature control based on this data. The number that was the same three times in a row is circled. By executing this, it is possible to ignore the thermistor data 15 that seems to have been affected by noise. However, when the sensor voltage is fluctuating as shown in Figure 4b, the thermistor data does not match three times in a row, making it impossible to capture valid data and therefore making temperature control impossible. It is a danger. Therefore, in Fig. 4c, when no new valid data is obtained even after time T has elapsed from point A where valid data was finally obtained, it is determined that temperature control is impossible at point B. However, by stopping heating, you can avoid falling into a dangerous situation. In addition, when heating is stopped based on the above judgment, the character display 17 indicating "stop" on the display tube 16 in Fig. 3
lights up or flashes to notify the user.

Next, the functions of the microcomputer 10 will be explained in detail based on FIG.

When the start key is pressed, cooking starts, so the heating operation begins. At the same time, sensor input is started to detect the heating state of the food.
That is, changes in the sensor 18 due to humidity and temperature are shaped or amplified by the sensor circuit 19, and this (that is, the voltage of the sensor circuit 19) is A/D converted by the A/D converter 20 at fixed time intervals. The A/D converted digital value is compared with the last A/D converted digital value input and held in the storage section 21, and if they match, the count of the counter 22 is incremented by one. Note that the data comparison is performed by the comparing section 23. If it does not match the previous digital value, the latest digital value is input and held in the storage section 21. At the same time, the counter 22 is cleared. On the other hand, when the comparator 25 detects that the value of the counter 22 has reached a predetermined number of times (the number of times stored in the predetermined value storage section 24), and the digital values match a predetermined number of times, this digital value is converted into valid data. The control unit 26 continues the heating control.The timer 27 counts the time, and if the digital values do not match for a certain period of time, the timer 27
is not cleared, an overflow occurs and a heating stop command is output to the control unit 26. As described above, according to this embodiment, even when effective thermistor data cannot be obtained due to noise, it is possible to prevent dangerous situations such as ignition due to excessive heating, and furthermore, the user is notified of this safety process. By doing so, some kind of countermeasure can be taken quickly and is extremely safe.

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

(1) By checking sensor data multiple times, infrequent noise can be ignored.

(2) When the frequency of noise becomes too high and valid sensor data cannot be obtained, temperature control will no longer be possible, so dangerous situations can be avoided by stopping heating.

(3) By notifying the user that heating has been discontinued, the user can quickly learn of this and take some countermeasures (for example, noise countermeasures) as soon as possible.

[Brief explanation of drawings]

Fig. 1 is a side cross-sectional view of a sensor-added heat cooker according to an embodiment of the present invention, Fig. 2 is a temperature control circuit diagram of the sensor-added heat cooker, Fig. 3 is an overall electrical circuit diagram of the same, and Fig. 4 FIG. 4a is a diagram showing the temporal change of the thermistor data when the frequency of noise is low in the same example, FIG. 4b is a diagram showing the thermistor data when the frequency of noise is high, and FIG. Explanatory diagram of the operation in which heating is stopped after a certain period of time has passed since valid thermistor data can no longer be obtained, No. 5
This figure is a functional block diagram of the electric circuit shown in FIG. 3. 1...Heating chamber, 2...Food, 6...Heater, 8
... Temperature sensor (thermistor), 10 ... Microcomputer (control unit), 14 ... Fixed resistance,
15...Noise, 16...Display tube, 17...Character display of "Cancel".

Claims (1)

[Claims] 1. A heating chamber in which an object to be heated is placed, a heating source coupled to this heating chamber, a control unit that controls power supply to this heating source, and a heating state or heating of an object to be heated. A sensor that detects the atmosphere such as room temperature and humidity, a sensor circuit that converts changes in electrical characteristics of the sensor due to temperature and humidity into a voltage as a sensor voltage, and an A/D converter that converts the sensor voltage into a digital signal inside the control section. A/D converter, a comparator that compares the digital value of the sensor voltage A/D converted by the A/D converter with the previous digital value at regular intervals, and a coincidence counter that counts the number of coincidences, and the control section starts heating and also controls the A/D of the sensor voltage.
Only when conversion is started and the count value of the coincidence counter counts a certain number of times, the digital value of the voltage of the sensor is judged as correct detection data, and heating control is continued and the count value of the counter is counted for a certain period of time or more. The sensor-added heat cooker is configured to determine that data from the sensor cannot be detected and stop heating when the number of times does not exceed a certain number of times. 2. The sensor-added heat cooker according to claim 1, wherein the control section has means for notifying the user when it is determined that data from the sensor cannot be detected.