JPS6115330B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooking device that supplies heating energy to a cooking chamber to perform cooking, and particularly to appropriately preheat the cooking chamber.

When heating energy is supplied to the cooking chamber to raise the atmosphere in the cooking chamber to a high temperature for cooking, the cooking chamber is first preheated, and after the cooking chamber reaches a predetermined high temperature, the food to be cooked is placed in the cooking chamber. You need to start cooking.

As preheating methods for this purpose, there are known methods such as performing preheating for a predetermined period of time and ending preheating when the cooking chamber temperature reaches a predetermined temperature. However, in the former method, the preheating time must be calculated each time in order to obtain the optimum preheating temperature depending on the type and amount of food to be cooked, the ambient temperature, etc., which is extremely complicated. In the latter method, the optimal preheating temperature can be easily obtained, but if the food to be cooked is not placed in the cooking chamber immediately after preheating and the cooking process begins, the temperature in the cooking chamber will drop and the preheating temperature will drop. The effect of heating cannot be expected.

The present invention has been made in view of the above points, and will be explained in detail in the following examples.

FIG. 1 shows an overview of an electric cooking device 10 according to this embodiment.

The cooking device 10 includes a cooking chamber 12 and a control panel 13 on the main body side, and a door 14 that is pivotally attached to the main body side and opens and closes the opening of the cooking chamber 12. door 1
A door clutch 17 and a door switch knob 18 are protruded from the inner periphery of the door 4, and when the door is closed, these enter into the main body to turn on the interlock switch and the door switch, respectively.

FIG. 2 shows details of the control panel 13, which is provided with numeric keys from 0 to 9, function keys for start, clear, preheat, cooking, and stop, and a temperature setting knob 20. . The temperature setting knob 20 is rotatable and has a temperature scale along its rotation locus.

FIG. 3 shows an electrical circuit diagram of the cooking device 10.

The electric heater 21 is connected to 60Hz commercial power supply terminals 24 and 25 via an interlock switch 22 and a bidirectional thyristor 23. This heater 21
is located within the cooking chamber 12 and serves as a heat source for supplying heating energy to the chamber. Interlock switch 22 is turned on by the door latch 17 described in FIG. 1, and bidirectional thyristor 23 is turned on when a voltage is applied to its gate through photocoupler 26. Therefore, when the photocoupler 26 operates with the door 14 closed, the heater 21 is driven.

The control power supply unit 27 includes a step-down transformer, a DC smoothing circuit, etc., and receives the power supply voltage from the commercial power supply terminals 24 and 25 and generates a DC power supply voltage Vc and a 60Hz forward wave signal voltage TB, which are distributed to each part of the circuit. .

The transistor 28 is for operating the photocoupler 26, and its ON/OFF state is controlled by a microprocessor 30 as a control means.

The microprocessor 30 has many input/output terminals, and the following description will focus on these input/output terminals.

The OS ₁ and OS ₂ terminals are circuit constant connection terminals for generating a synchronous clock inside the microprocessor, and a coil and a capacitor are externally connected to set the clock frequency at 400 KHz.

OB is a buzzer instruction terminal for generating a confirmation sound when the cooking chamber reaches a predetermined temperature due to preheating or when cooking is completed.When there is an output at this terminal, the transistor 31 is turned on and the buzzer 32 sounds.

IC ₁ is an input terminal for checking whether the door 14 of the microwave oven is open. That is, the door switch 33, which is turned on by the door switch knob ₁₈ described in FIG. 14 is released, and determines whether it is necessary to interrupt or prohibit its own operations.

RESET is an input terminal for resetting the internal state of the microprocessor 30 to the initial state when the microwave oven 10 is powered on. That is, when the power is turned on, the rise of the DC power supply voltage Vc is detected by the detection circuit 34 including a transistor and a Zener diode connected to the terminal RESET.
The detection force goes into the RESET terminal.

INT is an interrupt terminal, and the 60Hz signal TB is shaped into a 60Hz pulse signal by a waveform shaping circuit 35 consisting of transistors, diodes, capacitors, etc., and then input to the terminal INT. The microprocessor 30 interrupts other processing and executes timekeeping processing every time a 60Hz pulse signal is received. That is, a time signal such as a second signal is generated in synchronization with the pulse signal.

_G1 to _G4 are key input control terminals connected to each column line of the key matrix 36, and signals are sequentially output to each terminal during key input testing.

IK ₁ to _{IK 4} are key signal input terminals, each of which is connected to four row lines of the key matrix 36.

Each key switch of the control panel 13 (FIG. 2) is cross-connected to a predetermined intersection point of the column lines and row lines that constitute the key matrix 36, and when a key operation is performed on the control panel 13, the key switch corresponds to the corresponding key. at the intersection, the column lines and row lines forming the intersection are electrically connected via the key,
A signal is input to the terminals IK ₁ to _{IK 4} that are connected to the row line.

The microprocessor 30 therefore has terminals G ₁ to
The operated key is determined by checking the input signal states to the terminals _IK1 to _IK4 in synchronization with each output signal of _G4 .

IC ₂ is a temperature input terminal into which the output of the comparator 37 is input. The comparator 37 compares the respective output voltages of a temperature detecting section 39 including a thermistor 38 and a temperature setting section 41 including a variable resistor 40, and generates an output when the former is higher than the latter. The thermistor 38 is arranged near the wall of the cooking chamber 12 to detect the ambient temperature of the cooking chamber, and the variable resistor 40 is connected to the temperature control knob 20.
The resistance value is set depending on the position of (Fig. 2), and therefore, when the temperature of the cooking chamber 12 is higher than the temperature set by the temperature control knob 20, a signal is sent to the terminal IC _2. enters.

OT is a heating instruction terminal, and when there is an output at this terminal, the transistor 28 is turned on and the heater 21 is energized.

The microprocessor 30 is composed of a one-chip semiconductor integrated circuit, and mainly consists of ROM (read-only memory), RAM (random access memory, arithmetic unit, etc.), and executes work according to the program written in the ROM. do.

FIG. 4 shows the part after the start of heating in such a program. In addition, during such execution, various storage areas of the RAM are used, but those that appear in the following explanation are TIME, T ₁ to T ₃ , FLAG ₁
~ Each area of FLAG ₅ .

The operation of the cooking appliance 10 will be described below along with the control mode of the microprocessor 30.

In principle, each operation of the number keys, preheating key, and cooking key on the control panel 13 is accepted by the microprocessor when the cooker is in a standby state. In addition, in this standby state, all of the above RAM is cleared,
The microprocessor is in its initial state. For example, to preheat the cooking chamber 12 to 200°C and then cook at the same temperature for 20 minutes, press the preheat key in the standby state without putting food in the cooking chamber 12.
Operate the number keys □2, □0 and the cooking key in sequence,
Also, set the temperature control knob 20 to 200℃.

At this time, the number 20 representing the timer time is written in the TIME area of the RAM above, and FLAG ₁ and
1 is written in each area of FLAG ₂ , and the operation of the preheating key and cooking key is memorized.

The stored state can be cleared by operating the clear key and the cooker can be returned to the standby state.

Next, when the start key is operated, the microprocessor 30 starts heating according to the program shown in FIG.

In FIG. 4, each of the rectangular and diamond-shaped frames corresponds to an individual step of the program, and the numbers near each frame represent the step number. In principle, the program proceeds in the order of arrangement of each frame, starting from the step with the smaller step number to the step with the larger step number.
Depending on whether the judgment is established or not (that is, YES or NO) at the judgment step exceptionally represented by a diamond frame, the process moves to the appropriate step.

Generally, FLAGn←0 and
The steps marked as FLAGn←1 are each FLAGn
(n = 1 to 5) means writing 0 and 1 in the area, and FLAGn = 1? in the diamond frame? The step marked with means that it is determined whether the content of the FLAGn area is 1 or not.

The execution contents of each step other than the above are as follows.

S1: 5 is written as the number of buzzer notifications in the _T1 area.

S2, S29: Microprocessor input terminal IC ₁
It is checked whether the door 14 is in the closed state or not.

S4, S34: Microprocessor output terminal
A key input test is performed by outputting signals to _G1 to _G4 to determine whether or not the stop key has been operated.

S5, S31: Microprocessor input terminal
It was checked through the IC ₂ whether the cooking chamber temperature was higher than the temperature set by the temperature control knob 20.

S7, S25, S38, S36, S40: Turn off the output of the microprocessor output terminal OT.

S8, S32: Turn on the above terminal OT output.

S12: A numerical value representing 3 minutes as the buzzer notification interval is written in the T2 area.

S13: Turn on the output terminal OB output of the microprocessor.

S15: A numerical value representing 1 second as the buzzer sounding time is written in the _T3 area.

S16: Based on the aforementioned time signal formed based on the 60 Hz signal input to the input terminal INT of the microprocessor, the contents of each area of T ₂ and T ₃ are counted down as time passes.

S19: Turn off the output terminal OB.

S21: It is checked whether the contents of the _T2 area are 0 or not.

S23: The contents of the _T1 area are decreased by 1.

S24: It is checked whether the contents of the _T1 area are 0 or not.

S26, S37: An output is generated at the output terminal OB for only 2 seconds, and then the process moves to the following steps.

S33: Similarly to step S16, the contents of the TIME area are counted down as time passes.

S35: It is checked whether the contents of the TIME area are 0 or not.

S42: In the same way as step S4, it is checked whether the clear key is being operated.

S43: In the same way as step S4, it is checked whether the start key is being operated.

Now, after operating in the standby state as described above, when the start key is operated (assuming the door is closed), the program advances through steps S1 to S5, S8, and S9, and then from S2 to S9. S5, S8, S9
The first loop of At this time, since the step S8 is passed, the heater 21 is energized and the temperature of the cooking chamber begins to rise.

In the first loop circulation process, when the cooking chamber temperature exceeds the set temperature of 200°C, it is detected in step S5, and then in steps S6, S7, S9 to S1.
5, proceed through steps S17, S18, and S21. At this time, the heater 21 is deenergized in step S7, and the buzzer 32 starts sounding in step S13. The program then proceeds to S2-S7, S9, S
10, S16, S17, S18, S21, and during this time, the time elapsed is measured in S16. Therefore, when 1 second elapses during the second loop circulation, S
It is detected in step 18, and steps S19 to S2
Proceed through each step of step 1. At this time, since the buzzer 32 is deactivated in step S19, the buzzer 32 has been sounding for one second. The program is then S2
~S7, S9, S10, S16, S17, S21
The third loop of When the cooking chamber temperature drops below 200°C during the circulation of the third loop, the heater 21 is energized again through step S8, and thereafter, in the same manner, depending on the cooking chamber temperature, the third loop or S2 to S
5, S8 to S10, S16, S17, and S21, and thus the cooking chamber temperature is maintained at approximately 200°C.

When 3 minutes have passed during the circulation process of the third and fourth loops, the program moves from step S21 to step S2.
2 to S24, S2 to S7 (or S2 to S5, S
8), S9 to S15, S17, S18, and S21, and then the second loop is repeated.

Since the program steps proceed in the same manner from then on, the buzzer 32 will eventually indicate that the cooking chamber temperature is 200.
It sounds for 1 second when the temperature reaches °C, and then the same sound occurs every 3 minutes, while S23 sounds every 3 minutes.
As the temperature passes through the step, the time when the content of the _T1 area becomes 0, that is, after the temperature reaches 200℃ for the first time as described above.
After 15 minutes, the program enters step S25. Also, during these 15 minutes, the cooking chamber temperature is maintained at 200°C.

The program moves to step S25 and then
The process proceeds sequentially up to step 29, the heater 21 is turned off, and the buzzer 32 sounds for 2 seconds, after which the cooker enters the standby state.

After operating the start key, the program will continue until the cooking chamber temperature reaches the set temperature of 200°C, that is, when the door 14 is opened during the first loop circulation.
From step 2, move to step S40, then step S
Steps 41 to S43 are passed. Yotsute S40
Since the heater 21 is deenergized in the step, the heating is interrupted, and when the door 14 is thereafter closed and the start key is operated again, the preheating is restarted.

On the other hand, if the door 14 is opened within 15 minutes after the cooking chamber temperature first reaches the set temperature of 200°C, the program moves from step S2 to step S40.
Thereafter, the process goes through steps S41, S27 to S29, and then enters step S42. Therefore, when the door 14 is closed and the start key is operated again, the program will enter step S30 from step S3, and from then on, step S30 will be entered.
31, S32 (or S38), S33-S35,
The fifth loop of S2 to S3 is circulated, and during this period, S3
By passing step 2 or S38, the cooking chamber temperature is maintained at the set temperature of 200°C. In the circulation process of the fifth loop, the passage of time is measured in step S33, so when the set timer time of 20 minutes has elapsed, it is detected in step S35, and the program passes through steps S36 and S37 to start the heater 21. is de-energized, the buzzer 32 sounds for 2 seconds, and then the cooker goes into standby mode.

Therefore, during preheating, the door 14 is opened within 15 minutes after the cooking chamber temperature first reaches the set temperature of 200° C., and the door 14 is opened after the food to be cooked is placed in the cooking chamber 12.
By closing the door and operating the start key, the original heating cooking can be continued from the state where the cooking chamber is at the desired set temperature due to preheating.

In addition to the above operations, without operating the preheating key,
It is now clear that if the temperature control knob 20, □3, □0 numerical keys, the cooking key, and the start key are operated in sequence, preheating will not be performed, and cooking heating for 30 minutes will be performed immediately.

In the above embodiment, the electric heater is used as the heat source for both preheating and cooking heating, but microwave oscillation means is also provided, and either the electric heater or the microwave oscillation means can be selected as the heat source during cooking heating. It can also be used.

In addition, in the above embodiment, a digital numerical display means is provided to display the remaining time of the timer during cooking heating, or during preheating, after the cooking chamber temperature reaches the set temperature, the preheating is started after a certain period of time (15 minutes). You can also display the remaining time until it automatically ends.

Furthermore, in the above embodiment, the execution limit time for preheating is determined to be a certain period of time after the cooking chamber temperature first reaches the desired set temperature, but it may also be set to a certain period of time immediately after the start of preheating. . That is, a sufficiently long fixed time is assumed as the time required for the cooking chamber temperature to reach the desired set temperature for the first time, and then the preheating is stopped after the above-mentioned fixed time (15 minutes).

As is clear from the above description, according to the present invention,
Since the preheating of the cooking chamber is performed based on the set temperature, the desired preheating temperature can be easily set according to the type and amount of food to be cooked, the ambient temperature, etc. without calculating the preheating time each time. In addition, after the cooking chamber temperature reaches the desired preheating temperature, the cooking chamber is maintained at that temperature for a certain period of time, so you can put food into the cooking chamber at any time during this period and start cooking from the desired preheating temperature. It is very convenient to get started.

By the way, after the preheating of the cooking chamber is completed, the cooking start instruction means (corresponding to the start key in this embodiment) is normally operated when shifting to the original cooking heating. If the cooking start instruction means is operated by mistake even though there is no food to be cooked in the cooking chamber, cooking heating will start in an empty cooking state, and this state may change depending on the cooking conditions. It is dangerous as it lasts for a long time. Therefore, when transitioning to the original cooking heating, an additional operation is provided to end the preheating, and if the preheating is not completed, the transition from the preheating to the cooking heating is prohibited, thereby making it easier for the operator. It is possible to make the user aware of the transition from preheating to cooking heating, and it is possible to almost prevent dry cooking due to the above-mentioned erroneous operation. As an additional operation for terminating such preheating, a stop key operation may be selected as in this embodiment, but it is extremely meaningful to provide an operation for opening the door. In other words, when transitioning from preheating to cooking heating, under normal handling, the food to be cooked is always put into the cooking chamber and the door is inevitably operated.Therefore, as an additional operation as described above, Providing a door opening operation does not substantially increase the number of operating means and therefore does not increase the operational burden on the operator, and is effective in preventing empty cooking due to the above-mentioned erroneous operation.

Furthermore, if the additional operation described above is not performed within the preheating execution limit time, preheating will automatically end, so even if the cooker is placed in a safe place while in the preheating state, the preheating state will not change. It does not last forever, is extremely safe, and can prevent power wastage.

Furthermore, by setting the execution limit time of such preheating to a fixed time after the cooking chamber temperature first reaches the desired set temperature, it is possible to set the execution limit time of such preheating to a fixed time after the cooking chamber temperature first reaches the desired set temperature. This is effective because dead time can be eliminated from the execution limit time.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a cooking device according to an embodiment of the present invention, FIG. 2 is a plan view of the control panel of the cooking device, FIG. 3 is an electric circuit diagram of the cooking device, and FIG. 4 shows the operation of the cooking device. FIG. 21... Heater, 30... Microprocessor.

Claims (1)

[Scope of Claims] 1. A cooking chamber, a door that opens and closes the opening of the cooking chamber, a heating source that supplies heating energy to the cooking chamber, means for detecting the temperature of the cooking chamber, and means for detecting opening and closing of the door. , comprising a heating condition setting means for cooking heating, a preheating instruction means, and a control means, and the control means selectively executes the cooking heating and preheating depending on the presence or absence of an instruction from the preheating instruction means. During heating, the heating source is driven and controlled according to the conditions set by the heating condition setting means, and during preheating, the heating source is driven to maintain the cooking chamber at a predetermined temperature based on the output of the temperature detecting means. Once the temperature of the cooking chamber has reached the predetermined temperature, if the door opening/closing detection means detects the opening of the door within the preheating execution limit time, the preheating is immediately terminated, and the control is further performed. The means is a cooking appliance that prohibits transition from preheating to cooking heating unless the preheating is completed. 2. The cooking appliance according to claim 1, wherein the control means automatically ends the preheating if there is no operation to end the preheating within the preheating execution limit time. 3 In claim 1 or 2,
A cooking device characterized in that the preheating execution limit time is a certain period of time after the cooking chamber temperature first reaches the predetermined temperature.