JPS6012754B2 - microwave oven - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave oven whose high frequency output can be variably controlled.

Generally, in this type of microwave oven, the power to the magnetron is turned on and off by a switch that responds to a rotating cam.
And by switching the on-off duty,
The high frequency output (average output) of the magnetron is variably controlled.

However, if you want to vary the output while cooking at a predetermined output, you may manually select and switch the cam that determines the on-off duty of the switch, or use a lever that works with the timer for setting the cooking time. This was done by selectively switching the cam. However, in the former case, this conventional method is very inconvenient to use, and in the latter case, the relationship between the timer setting time and the output is set to 400 watts at the beginning and 100 watts at the end.
It was difficult to make a change such as oo watts regardless of the set time. The present invention has been made in view of the above circumstances, and its purpose is to simply set a desired cooking time in advance, and to arbitrarily and arbitrarily control the high frequency output during cooking, regardless of the set cooking time. It is an object of the present invention to provide a microwave oven that can be automatically varied and is extremely convenient to use.

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

In FIG. 1, reference numeral 1 denotes a heating chamber, and a shelf board 2 is provided in the heating chamber 1, on which a cooked food 3 is placed.

Further, a magnetron 4 is mounted on the ceiling surface of the heating chamber 1, and high frequency waves from the magnetron 4 are supplied into the heating chamber 1. The magnetron 4 is connected to the secondary side of a high voltage transformer 6 via a rectifier circuit 5. The primary side of the transformer 6 is connected to an AC power source 8 through a switching element, such as a bidirectional thyristor 7, and a normally open contact 15a of a relay 15, which will be described later, in series. On the other hand, numeral 9 denotes a time control section, which controls the operating time and output switching time of the magnetron 4, and is configured as shown in FIG. 2, for example.

That is, ~ 21 is a setting section for setting a desired time numerically, and this is composed of a numeric keypad, function keys, etc., and is provided on the operation panel.
The numerical data set by the setting section 21 is sent to the first counter 23 and the second counter 24 via the input control section 22.
, , 242, respectively. Above 1st counter 2
3 is an operation time control counter for controlling the operation time of the magnetron 4, that is, the cooking time, and when numerical data is set from the input control section 22 and a pulse is supplied from a gate circuit 27, which will be described later, the pulse is When the count value reaches "0", the output signal T changes from the "0" level to the "1" level. Further, the second counters 24, 242 are output switching time control counters for controlling the time for switching the output of the magnetron 4, and are set with numerical data from the input control unit 22, and are set in the gate circuit 27, which will be described later. When a pulse is supplied from , it counts down according to the pulse, and when the content becomes "0", the output signal T2
, T3 change from the "0" level to the "1" level. On the other hand, 25 is a pulse generator which generates a reference time clock pulse with a cycle of, for example, 1 second. The pulses output from this pulse generator 25 are supplied to a frequency divider 26. This frequency divider 26 divides the frequency of the pulse from the pulse generator 25 and outputs each pulse of, for example, a 1' Kagami period and a 2/Kyakusha period. The above minuter 26
Each pulse output from the pulse generator 25 is supplied to the gate circuit 27 together with the pulse from the pulse generator 25. This gate circuit 27 opens when the FF circuit 12 (described later) is set, and sends a 1 second period pulse from the pulse generator 25 to the first counter 23, and a 1' inspection period pulse from the frequency divider 26. The pulse is sent to one of the second counters 24,
and 2/3 second period pulses from the frequency divider 26 are supplied to the other second counter 242, respectively. Each output signal T, , L, T3 of the time control section 9 is supplied to an output control circuit 10'.

This power control circuit 10 operates the thyristor 7 on and off in response to the signals T, , T2, and T3, and controls the on-off duty to supply power (average value) to the magnetron 4. This circuit sequentially variably controls the average output of the magnetron 4 in three stages by varying the output voltage, and is configured, for example, as shown in FIG. It is supplied to one input terminal of the circuit 32.
The signals T2 and T3 are supplied to AND circuits 322 and 3, respectively.
23 is supplied to one input terminal of each. Above AND circuit 3
2, the signal T2 is supplied to the other input terminal of the inverter circuit 312, and the signal L is supplied to the other input terminal of the AND circuit 322 via the inverter circuit 313.
The output of the inverter circuit 31 is supplied to the other input terminal of the AND circuit 323. The analog switch 33 is activated by the output of the AND circuit 32, and the analog switch 332 is activated by the output of the AND circuit 322.
The analog switches 333 are controlled to be turned on and off by the outputs of the analog switches 333 and 333, respectively. On the other hand, 34 is, for example, a shift register with one slave stage, and this register 3
4 is outputted from the signal generator 35 to the data input device 4.
1'' signal is supplied, and the clock pulse input terminal is supplied with a 1 second cycle pulse outputted from the pulse generator 25 of the time control section 9. 1” signal to pulse generator 25
It shifts sequentially from the 1st stage in response to the pulses from the 1st stage, and when the outputs Q and O of the final stage, that is, the 10th stage, reach the "1" level (after 1 town), the IJ is set and the process is repeated from the beginning. There is. Therefore, for example, the outputs Q2, Q4, and Q6 of the second, fourth, and sixth stages become output signals with different duties as shown in FIG. 4, respectively. Thus, the output Q2 of the second stage of the shift register 34 is passed through the analog switch 33, the output Q4 of the fourth stage is passed through the analog switch 332, and the output Q6 of the sixth stage is passed through the analog switch 333. V is supplied to the OR circuit 36 via the respective OR circuits 36. The output of this OR circuit 36 is supplied to a gate control circuit 37. This gate control circuit 37 supplies a gate signal corresponding to the output of the OR circuit 36 to the gate of the thyristor 7 to turn the thyristor 7 on and off. Further, the output signal T of the time control section 9 is supplied to the reset input terminal of the FF circuit 12 via the differentiating circuit 11.

The FF circuit 12 is set when the cooking switch 13 is pressed, and its set output is supplied to the drive circuit 14. The drive circuit 14 drives the relay 15. Next, the operation in the above configuration will be explained.

First, set the desired cooking time. That is, setting section 2
1, for example, 120 seconds, that is, the numerical value "120" is set. This set numerical data is input to the input control unit 2.
2 to the first counter 23 and the second counter 24.
, 242 and set therein.
Therefore, the contents of each of the counters 23, 24, 242 are "120". At this time, the output signals T, T2, T of each of the counters 23, 24, 242 are
3 are respectively at the "0" level, and as a result, only the AND circuit 32 is established, its output becomes the "1" level, and only the analog switch 33 is turned on. On the other hand, the shift register 34 operates as described above,
Signals as shown in FIG. 4 are sequentially outputted from the respective outputs Q2, Q4, and Q6. Therefore, in this case, since the analog switch 331 is on, the output Q6 is selected and its signal is supplied to the gate control circuit 37. Thereby, the gate control circuit 37 supplies the gate of the thyristor 7 with a gate signal corresponding to the signal from the output Q6. When the cooking switch 13 is pressed, the FF circuit 12 is set and the relay 15 operates, and its normally open contact 1
5a is closed.

In this case, the thyristor 7 repeats an on-off operation in response to a signal from the gate control circuit 37, and power is supplied to the magnetron 4 in accordance with the on-off operation. Therefore, the magnetron 4 operates intermittently to supply high frequency waves into the heating chamber 1, and cooking of the cooked food 3 is started. In this case, the signal of the output Q6 of the shift register 34 has a duty of 6/10 (that is, a "1" level for 6 seconds and a "0" level for 4 seconds).
” level), the t-gate control circuit 37 repeats the operation of turning on the thyristor 7 for 6 seconds and turning it off for 4 seconds.As a result, the magnetron 4 operates in oscillation according to the above-mentioned on-off duty. The average output is in a high output state.On the other hand, when the FF circuit 12 is set, the gate of the gate circuit 27 is opened, so that the pulse with a period of 1 second from the pulse generator 25 is coupled to the first counter 23. Further, the pulse with a period of 1'3 seconds from the frequency divider 26 is sent to the second counter 24, and the pulse with a period of 2'3 seconds is sent to the second counter 24.
The signals are respectively supplied to the counter 242. therefore,
The first counter 23 counts every second, and one second counter 23 counts every second.
The counter 24 counts every 1/nail cutting, and the other second counter 242 counts every 2' sand. Thereafter, when four currents have elapsed, the content of the second counter 24 becomes "0" and its output signal T2 becomes "1" level.

In this case, the AND circuit 32 is not satisfied and the analog switch 331 is turned off, and conversely, the AND circuit 3 is not established.
22 is established, and only the analog switch 332 is turned on. Therefore, the output Q4 of the shift register 34 is selected and its signal is supplied to the gate control circuit 37. In this case, the signal of the output Q4 has a duty of 4/
10 (ie, "1" level for 4 seconds and "0" level for 6 seconds), the gate control circuit 37 repeats the operation of turning on the thyristor 7 for 4 seconds and turning it off for 6 seconds. As a result, the magnetron 4 operates in oscillation according to the above-mentioned on-off duty, so its average output decreases and enters a medium power state. When a further period of time elapses in this state, and 8 current stages have passed, the content of the second counter 242 becomes "0" and its output signal T3 also becomes "1" level. In this case, the AND circuit 322 is not established and the analog switch 332 is turned off, and conversely, the AND circuit 323 is established and the analog switch 333 is turned on. Therefore, the output Q2 of the shift register 34 is selected and its signal is supplied to the gate control circuit 37.
In this case, the signal of the output Q2 has a duty of 2/
10 (ie, "1" level for 2 seconds and "0" level for 8 seconds), the gate control circuit 37 repeats the operation of turning on the thyristor 7 for 2 seconds and turning it off for 8 seconds. As a result, the average output of the magnetron 4 further decreases, resulting in a low output state. Further time passes in this state, and when 120 seconds have elapsed, the content of the first counter 23 becomes "0".
”, and its output signal T also goes to the “1” level. In this case, the AND circuit 323 is not satisfied and the analog switch 333 is turned off, and all the analog switches 33, 332, and 333 are thus turned off. As a result, the output of the shift register 34 is no longer coupled to the gate control circuit 37, so the thyristor 7 stops its on-off operation and enters a continuous off state. Therefore, the magnetron 4 stops its oscillation operation and ends the heating cooking. Moreover, when the signal T, becomes "1" level,
The FF circuit 12 is reset by the rising edge, thereby deenergizing the relay 15 and opening its normally open contact 15a to prepare for the next operation. In this way, the first counter 23 for controlling cooking time and the second counter 23 for controlling output switching time
Counters 24, 242 are provided, the first counter 23 counts in reference time units, and the second counter 24, 242
is set to be shorter than the reference time and counted in hours, and when the second counters 24, 242 reach "0", the output of the magnetron 4 is changed by switching the on-off duty of the thyristor 7. It is variable controlled.

Therefore, the on-off duty of thyristor 7 is
As shown in FIG. 5, the output of the magnetron 4 changes sequentially with respect to the set time, and as shown in FIG. 6, the output of the magnetron 4 gradually decreases. As a result, simply by setting the cooking time, the output can be automatically and variably controlled during the cooking process regardless of the cooking time. This is particularly effective for thawing and heating frozen foods, for example. In other words, water generally absorbs radio waves more easily than ice, so if you defrost it at a constant output, there will be parts that have not yet been defrosted, while others have reached tens of qo. arise. For this reason, it is said that it is effective to decompress at a low output after partial decompression is performed, and this can be easily implemented. Next, a modification of the time control section 9 shown in FIGS. 7 and 8 will be described.

Note that the same parts as in FIG. 2 are denoted by the same reference numerals and detailed explanations will be omitted. First, in FIG. 7, a data transfer control section 28 and a third counter 29 for output switching are added, and the second counter is reduced to one, but they are connected as shown in the figure. That is, the frequency divider 26 first outputs a pulse with a period of 1/3 second. When a numerical value ("120" as in the above description) is set in the setting section 21, the numerical data is set in the first counter 23 and the second counter 24. At this time, the third counter 29 sets only its output signal P to the "1" level. When the cooking switch 13 is pressed and the FF circuit 12 is set, a 1 second period pulse from the pulse generator 25 is sent to the first counter 23, and a 1/3 second period pulse from the frequency divider 26 is sent to the first counter 23. The signals are supplied to the second counter 24, respectively. Therefore, since the second counter 24 counts every 1/3 second, its contents become "0" after four seconds have elapsed. As a result, the third counter 29 counts "11" and its output signal P2
At the same time, the data transfer control unit 28 sets the content of the first counter 23 at this time (the numerical value "80") to the "1" level.
'') is transferred to the second counter 24, and the frequency divider 26 then outputs a pulse with a period of 2/3 seconds. Therefore, since the second counter 24 counts every 2/inspection, the contents become "0" again after 4 more passes. As a result, the third counter 29 is again set to "
11'' and only the output signal P3 is set to the ``1'' level. When this signal P3 reaches the "1" level, the operation of the data transfer control section 28 is prohibited. After 12 cycles have elapsed, the content of the first counter 23 becomes "0", and the FF circuit 12 is reset by its output signal. Next, FIG. 8 shows a data transfer control section 28 similar to that in FIG.
A third counter 29 is added, a storage section 30 is added, these are connected as shown in the figure, and the frequency divider 26 generates only pulses with a 1' period. That is, when a numerical value ("120" for the same machine as in the above description) is set in the setting section 21, the numerical data is stored in the storage section 3.

Then, this stored numerical data (120) is transferred to the first counter 23 and set there, and is also transferred by the data transfer control section 28 to the second counter 24 and set there. At this time, the third counter 29 sets only its output signal P to the "1" level. When the cooking switch 13 is pressed and the FF circuit 12 is set, the 1 second cycle pulse from the pulse generator 25 is sent to the first counter 2.
3, a pulse with a period of 1/3 second from the frequency divider 26 is supplied to the second counter, respectively. Therefore, since the second counter 24 counts every 1/nail sand, its contents become "0" after 4 sands have passed. As a result, the third counter 29 sets only its output signal P2 to the "1" level, and the data transfer control section 28 sets the setting data (120) in the storage section 30 in the second counter 24 again. Therefore, the second counter 24 counts again every 1/lactic acid, and the content becomes "0" again after 4 hours have passed. This causes the third counter 29 to output its output signal P3.
only to the “1” level. When this signal P3 reaches the "1" level, the operation of the data transfer control section 28 is prohibited.
After 120 seconds have elapsed, the content of the first counter 23 becomes "0", and the output signal causes the FF circuit 12 to
This is to reset the . Even with these configurations, not only can the same effects as those of the above-mentioned embodiments be obtained, but only one second counter is required.

Moreover, by doing as described above, the output control circuit 10 becomes as shown in FIG. 9, and the inverter circuits 311 to 313 and the AND circuits 32 and 323 can be omitted.
In FIG. 8, the counters 23 and 24 are counted down, but by making them count up and comparing the count contents with the contents of the storage section 30, the output signals P, , P2, P3 are obtained. It is also possible to make In this case, when the contents of the second counter 24 match the contents of the storage section 30, the second counter 24 is reset. In the above embodiment, a case has been described in which the output of the magnetron is variably controlled in three stages, but the invention is not limited to this. For example, by increasing the number of second counters or the types of pulses supplied to the second counters,
It is also possible to change in multiple stages of three or more stages.

In addition, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

As described in detail above, according to the present invention, there is provided an operation time control counter that counts in units of reference time and controls the operation time of the magnetron, and at least one counter that operates in units of time shorter than the reference time. A counter for controlling the output switching time is provided, and when the content of the counter for controlling the output switching time reaches the set value, the output of the magnetron is variably controlled, so all you have to do is set the operating time of the magnetron, that is, the cooking time. The microwave oven is extremely convenient to use, as it can arbitrarily and automatically vary the high-frequency output during cooking, regardless of the set cooking time, and does not require the cumbersome and inconvenient key mechanism of conventional methods. Can be provided.

[Brief explanation of drawings]

The figures show one embodiment of the present invention, in which Fig. 1 is an overall schematic block diagram, Fig. 2 is a block diagram of a time control section, Fig. 3 is a block diagram of an output control circuit, and Fig. 4 is a block diagram of an output control circuit. A diagram showing the output state of the shift register, FIG. 5 is a diagram showing the change state of the duty with respect to the set time, FIG. 6 is a diagram showing the change state of the output with respect to the set time, and FIGS. 7 and 8 are the time control section. FIG. 9 is a configuration diagram showing a modification of the output control circuit. 1... Heating chamber, 4... Magnetron,
7...・Switching element (thyristor), 8・
...Power supply, 9...Time control section, 10...
Output control circuit, 21...setting section, 23...
1st counter (operation time control counter), 24, 24
,, 242... Second counter (power switching time control counter), 25... Pulse generator, 26... Frequency divider, 29... Output switching counter, 34...・・・
...Shift register. Figure 5 Figure 6 Figure 1 Figure 2 Figure 3 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1. A heating chamber, a magnetron that supplies high frequency waves into the heating chamber, a setting section for setting the heating time, and a counting operation according to the setting contents of this setting section in standard time units, so that the operating time of the magnetron can be adjusted. an operation time control counter to be controlled, at least one output switching time control counter that performs a counting operation in accordance with the setting contents of the setting section in units of time shorter than the reference time, and according to the contents of these counters; 1. A microwave oven comprising: an output control circuit for selectively outputting pulse signals with different on and off duties; and means for controlling energization of the magnetron in accordance with the pulse signals selectively output by the output control circuit.