JPH0817112B2 - High frequency heating equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high-frequency heating device using a microcomputer.

2. Description of the Related Art A high-voltage capacitor on the secondary side of the main circuit of a high-frequency heating device uses a capacitor whose capacity varies depending on the power supply frequency, but a capacitor using a microcomputer (hereinafter referred to as "microcomputer") It is common to have a configuration in which the frequency is judged by a microcomputer and the capacitance of the capacitor is electrically switched at the same time. The circuit configuration is shown in FIG. 7, and 8 is a capacitor capacity changeover switch which is opened / closed by an output signal from the microcomputer. Reference numeral 10 is a magnetron, 9 is a main relay for oscillating the magnetron, 13 is an internal lamp, 14 is a cooling fan, 12 is a door switch, and 15 is a discharge resistor for discharging the electric charge remaining in the high voltage capacitors 16 and 17. Is. The operation of this circuit is, for example, when the power supply frequency is 60 Hz, the contact a of the changeover switch 8
Is open and charging / discharging is performed only by the capacitor 16.
When the microcomputer 11 determines that the frequency is 50 Hz, the microcomputer issues a signal to the changeover switch 8 to close the contact.
In this state, the magnetron oscillates with capacitors 16 and 17
Is done by. The timing for outputting a signal for switching the capacity of the high voltage capacitor by the microcomputer and the timing for outputting a signal to the main relay 9 which opens and closes to oscillate the magnetron 10 are as shown in FIG. That is, only when the power supply frequency is 50 Hz, the signal to the changeover switch 8 is output in synchronization with the signal to the main relay 9, and both signals are turned off at the end of cooking.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In a cycle-free high-frequency heating device, when the signals are controlled as described above, only the capacitor 16 is charged with the contact of the changeover switch 8 opened.
It is not charged to 17, and when cooking is finished, the condenser
The electric charge charged in 16 is discharged by the discharge resistor 15. However, when the magnetron is oscillated with the contact a of the changeover switch 8 closed, the electric charge is charged to both the capacitors 16 and 17, but the switch 8 is cut off at the end of cooking, so the electric charge accumulated in the capacitor 17 is accumulated. Is not discharged. Under these circumstances, if you open the body for some reason (for example, due to a set failure),
It is extremely dangerous even if it is unplugged. When repairing a set, there is always the problem of this kind of danger.

Therefore, the high-frequency heating device of the present invention, by shifting the timing of outputting a signal to the capacitor changeover switch and the main relay, to quickly charge and discharge the capacitor, further power supply at the time of plug-in The control means is provided for discharging the electric charge accumulated in the capacitor by closing the changeover switch for a certain time regardless of the frequency.

Action According to the present invention, even when cooking is performed with the changeover switch turned on, both capacitors can be discharged quickly because the state in which the changeover switch is turned on is maintained for a certain period of time after the end of the cooking. Also, when the plug-in is turned on, the changeover switch is turned on so that no charge remains in the capacitor, which is safe.

Example Hereinafter, an example of the present invention will be described. FIG. 2 is a perspective view of the main body of the high-frequency heating device of the present invention. Body 20
A door 202, a display tube 7 and a key operation unit 204 are provided on the front surface of 1. 203 is a heating chamber for food. FIG. 1 shows a block diagram of the embodiment. The signal from the power supply 1
It is judged by the power supply frequency judging means 4 in the microcomputer 11, and the control means 6 outputs a signal to the high-voltage capacitor changeover switch 8 according to the frequency. Further, the data of the established cooking is entered in the cooking setting means 5 by the signal from the cooking setting key 2 in the key operation unit 204, and the control means 6 controls the power source frequency together with the signal from the cooking start instructing means 3. The signal is output to the capacitor changeover switch 8 together with the signal from the determination means 4 and the relay which is the load control means 9 is turned on and off, whereby the magnetron which is the heating means 10 oscillates and cooking is performed. At the same time, the control means 6 outputs various information to the fluorescent display tube, which is the display means 7, to display it.

FIG. 3 shows the timing of the changeover switch signal and the main relay signal of this embodiment. At the time of plug-in, the switch 8 is turned on for a sufficient time (for example, 15 seconds) to discharge the electric charge remaining in the capacitor regardless of the power supply frequency. When cooking is set and the start key is pressed, only in the case of the 50Hz specification, first the changeover switch 8 is turned on, and the main relay 9 is turned on after waiting for a time (for example, 1 second) for the state to stabilize, and the cooking setting is made. Accordingly, the main relay 9 is appropriately continued to obtain the desired output of the magnetron. When the cooking is completed, the main relay 9 is first turned off, then the capacitor is discharged and the changeover switch 8 is turned off after a certain time (for example, 15 seconds).

A microcomputer program for realizing the above control means will be described with reference to a flowchart.

FIG. 4 shows control during plug-in. At P1 at the same time as the plug-in, the power supply frequency is determined and the result is stored in the memory. At P2, data is put into a timer (T1) in the memory (in this embodiment, data suitable for counting 15 seconds) and activated. The signal of the changeover switch is output at P3. The timer (T1) is decremented at P4, and the switch 8 remains ON until it is ended (P5). After a certain period of time, the switch 8 is turned off at P6.

FIG. 5 shows the control immediately after the start of cooking. When the cooking start designation key 3 is pressed, the cooking in progress (F) is set to 1 at P7. P8
, Determine if the power supply is 50Hz, and if NO, go to P13, y
If it is es, proceed to P9 and start the timer (T2). At P10, the changeover switch 8 is turned on and the process goes to P11. At P11, the timer (T2) is decremented, which is 1 second in this embodiment, but when T2 ends (P12), the program proceeds to P13 to turn on the main relay 9 and the oscillation of the magnetron starts.

FIG. 6 shows a program during and after cooking. In P14, it is judged whether cooking (F) is 1 or not. If it is 1, P20 in P15 if the timer (T3) is in operation, P16 if NO.
Decrement the cooking time with, and determine if it ends with P17. If yes, go to P18 and turn off the main relay 9 to stop the magnetron oscillation. If P19 determines if it is 50Hz or not, if yes, P20 will start the timer (T3) at the end NO
In case of, since cooking is completed, the process proceeds to P23. Timer (T3)
Is running, decrement at P21 and finish at P22. At P23, set cooking (F) to 0, clear the timer (T3) (P24), and turn off the signal of the changeover switch at P25 to finish. To do.

As described above, the timing control shown in FIG. 3 can be realized.

EFFECTS OF THE INVENTION As is apparent from the above description of the embodiments, according to the present invention, the following effects can be obtained.

(1) It is safe even during repairs because the capacitor can be fully discharged at the end of cooking.

(2) Even if the plug is unplugged at the same time as the cooking is completed, the capacitor can be discharged when plugging it in again, and the risk is lower.

[Brief description of drawings]

FIG. 1 is a block diagram of a high-frequency heating apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view thereof, FIG. 3 is a timing chart thereof, FIG. 4 is a main circuit diagram thereof, and FIGS. FIG. 7 is a circuit diagram of the conventional example, and FIG. 8 is a timing chart of the conventional example. 1 ... Power supply part, 2 ... Cooking setting key, 3 ... Cooking start instruction key, 4 ... Power frequency determination means, 5 ... Cooking setting means, 6 ... Control means, 7 ... Display means, 8 ... … Condenser changeover switch, 9 …… Load control means (main relay), 10 …… Heating means (magnetron), 11 …… Microcomputer.

Claims (1)

[Claims] 1. A heating chamber for containing food, a high-frequency oscillator for supplying a high-frequency output to the heating chamber, a power supply unit for supplying power to the high-frequency oscillator, and a power supply frequency determining means for determining a power supply frequency during use. And a switch for switching the capacity of the high-voltage condenser that constitutes the power supply unit to an appropriate capacity according to the power supply frequency, and heating means for starting and stopping food, cooking time, control means for controlling heating output means, and the like, The controller closes the switch for a certain period of time when the power is connected, and when the power source frequency determination means determines that the switch is closed, the controller closes the switch for a certain period of time after the cooking is completed. High-frequency heating device configured to hold in this state.