JPS58145830A - High frequency heater - Google Patents

Abstract

PURPOSE:To make it possible to detect humidity accurately at all times by a method wherein more than two kinds of cleaning temperatures of cleaning methods are used on a humidity sensor so that the original characteristic of the humidity sensor is maintained for a prolonged period of time. CONSTITUTION:An air intake port 7 and an air exhaust port 8 are provided in a heating chamber 6 and air is sucked into, and discharged from, the heating chamber by means of a fan 4. Further, the humidity sensor 9 is provided adjacent to the exhaust port 8 of the heating chamber 6 and a self-cleaning device 9b by heating is provided in the humidity sensor 9. In this case, two kinds of cleaning temperatures are set on the humidity sensor and the cleaning of the high temperature side of the humidity sensor is carried out periodically or every predetermined time during an integrated cooking time. Further, two kinds of long and short cleaning times are set on the humidity sensor and the long time cleaning of the sensor is carried out periodically or every predetermined time during the integrated cooking time. As a result, the original characteristic of the humidity sensor can be maintained for a prolonged period of time and the detection of humidity can be carried out accurately at all times to thereby make it contribute to the automatization of the high frequency heater.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-frequency heating device that is equipped with a humidity detector that detects water vapor and the like from food and that automates cooking.

With the introduction of microcomputers, the operating methods for high-frequency heating devices have become digital and multifunctional, but on the other hand, the operability has deteriorated as they cannot be operated without following complicated procedures. As a result, efforts are being made to automate cooking by using various sensors and combining them with the functions of microcomputers. Among these methods, methods that detect steam and gas from food do not come into contact with the food, so they do not damage the food.
It also saves time and effort, so the effects can be said to be very impressive. However, in order to detect vapors and gases from food, the detector must be exposed to the atmosphere, which poses the problem of contamination. Contamination of the detector can lead to cooking failure, overheating and carbonization of the food, and even a fire.

Page 3 In addition, as a method for detecting humidity and gas, there are methods to control a high-frequency oscillator by detecting the point at which humidity or gas starts to appear, the point at which it suddenly changes, or the point at which it is saturated, and to detect the amount of change in humidity or gas. There are methods such as measuring and using the time it takes to reach the amount of change. The former is a rough detection method and limits the types of cooking and the range of environments that can be automated, but slight contamination of the detector is not a problem. The latter allows detailed automation of tasks such as defrosting frozen foods, cooking eggs, or adjusting the finish of meat, but it also ensures that the characteristics of the detector are always stable, as even the slightest dirt on the detector will not affect the cooking results. There is a need to maintain The present invention is particularly aimed at preventing contamination of humidity detectors in high-frequency heating devices that require highly accurate control performance, such as the latter.

FIG. 1 is an external view of a high-frequency heating device showing an embodiment of the present invention, in which 1 is a control section including a microcomputer, 2
2 shows a door, and 3 shows an exhaust port. FIG. It is exhausted from the exhaust port 8 provided on the wall surface of the heating chamber 6 along with gas and gas, passes through a humidity detector 9, and is discharged from the exhaust port 3 provided on the body. 1o is an air guide provided to adjust the speed or volume of air applied to the humidity detector 9. Unfortunately, with this configuration, the humidity detector 9 will be constantly exposed to food steam not only during automatic cooking but also during manual cooking, and if there is no cleaning/ Contamination will be significant.

Figure 3 shows a humidity detector 9 with a self-cleaning function.
, which is a perspective view of a humidity detection element 9-IL and a cleaning heater 9-b, in which the cleaning heater s-b heats the humidity detection element 9-a to a high temperature and uses the heat to burn off dirt. It is. Further, the humidity detection element 9-a exhibits a thermistor characteristic in an atmosphere of 150' (::), and by utilizing this, the cleaning temperature can be managed.

FIG. 4 on page 5 is a wiring diagram of the present high-frequency heating device, in which power is constantly supplied from a power plug 11 to a low voltage transformer 13 via a fuse 12. The control circuit 14 including the microcomputer operates according to the operation input from the keyboard 16.
Display tube 16 and main switch 20. The reed switch 24 for intermittent high-frequency oscillation is operated, and the cleaning heater 9-
Cleaning of the humidity detection element 9-IL by the controller b, detection of humidity, notification of completion of cooking by a buzzer (not shown), etc. are all controlled. 17,18. and 19 is door 2
4 indicates a cooling fan. Further, a capacitor 22 and a diode 23 perform half-wave voltage doubler rectification to supply high-voltage power to the magnetron 5 via a high-voltage transformer 21 .

FIG. 5 shows the degree of recovery from contamination by cleaning the humidity detection element 9-IL and the state of deterioration.

Contaminants adhering to the humidity detection element 9-IL can be removed to some extent by heating the humidity detection element 9-IL to a temperature of 400° C. or higher using the cleaning heater 9-b, and the 6-Beno effect becomes more pronounced as the temperature increases. However, if the leaning is repeated in this manner, the characteristics of the humidity detection element 9-a gradually change, and the degree of change becomes larger as the temperature increases. As mentioned above, the cleaning temperature of the humidity detection element 9-IL is controlled by the resistance value of its thermistor characteristics, so the resistance value detected during cleaning is an average value, and there are high temperature areas and low temperature areas. . Furthermore, if the humidity detection element 9-IL is left in a contaminated state for several days to several tens of days, it will be difficult to restore its characteristics by cleaning. Because of this relationship, cleaning is required to be performed at a lower temperature, less frequently, and more effectively. From another point of view, since humidity cannot be detected during cleaning, it is necessary to stop high-frequency oscillation, and this condition will cause the high-frequency heating device to lose its excellent feature of speed cooking. It is desirable to have less. Therefore, at the beginning of automatic cooking that requires humidity detection, cleaning is quickly performed at 400°C, and after cooking is complete, thorough baking is performed at 500°C. Alternatively, in order to reduce the number of cleanings at 6oo'C and prevent it from being left contaminated for a long time, cleaning at 500℃ once a day at night, and keeping the total cooking time to a certain amount of time. If the temperature reaches 500'C, there is also a method of cleaning at 500'C after the completion of cooking.

Another method is to reduce the variation in temperature of the humidity detection element 9-a during cleaning as described above, in other words, by increasing only the temperature of the low temperature part, even if the temperature is maintained at the same temperature, cleaning The effect will be greater.

In other words, by keeping the temperature at 40°C for about 1 minute, the deterioration of the humidity detection element 9-ya due to the number of cleanings can be suppressed to a lower level than at soo°C, and the degree of recovery from contamination can also be reduced to 50°C.
It becomes comparable to cleaning at 0°C. However, it is not preferable to use this method at the beginning of automatic cooking from the viewpoint of speedy cooking.

As described above, according to the present invention, the original characteristics of the humidity detector can be maintained for a long period of time, and accurate humidity detection can be performed at all times, which is greatly useful for automation of high-frequency heating equipment.

[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 partially cutaway view of the same plan view, FIG. 3 is a perspective view of a humidity detector with a self-cleaning function, and FIG. The figure is an electrical wiring diagram, and FIG. 6 is a diagram showing changes in characteristics of the humidity detection element due to contamination or cleaning. 9-IL...Humidity detection element, 9-b/old...Cleaning heater, 14...Control circuit.

Claims (1)

[Scope of Claims] (1) A heating store, an intake port and an exhaust port provided in the heating store, a fan motor for intake and exhaust, and a humidity detector provided near the exhaust port; This high-frequency heating device is equipped with a heating self-cleaning device installed in the humidity detector, and can set two or more types of cleaning temperatures or methods. @) The high-frequency heating device according to claim 1, wherein the cleaning has two types of set temperatures, and the cleaning on the high temperature side is performed periodically or at fixed intervals of the cumulative cooking time. (3) The high-frequency heating device according to claim 1, wherein the cleaning is performed using two types of cleaning time, and the cleaning on the long-term side is performed periodically or every fixed time of the cumulative cooking time. 2beno