JPS6018185Y2 - electric rice cooker - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electric rice cooker that has a built-in microcomputer that stores an automatic rice cooking program.

Conventional electric rice cookers set the cooking power in advance according to the amount of rice to be cooked, and when the amount is small, the power is lowered to suppress the sudden rise in temperature of the rice and smoothly absorb water into the vermilion meat before boiling. Also, when the quantity is large, set the power to maximum so that the rice temperature rises quickly and boils quickly.
When the time comes for boiling, a built-in timer that is set in advance according to the amount of rice to be cooked is activated, switching to the power necessary to sustain boiling, and then lowering the power for cooking.

When there is no moisture at the bottom of the inner pot and the heat-responsive switch installed at the bottom of the inner pot turns off, the rice temperature reaches the temperature required for so-called a conversion, which is %℃ or higher, so that delicious rice can be cooked. ing.

However, before cooking, be sure to press the operation button to specify the amount of rice to be cooked, set the appropriate power, and then set the built-in timer to predict how long it will take to boil the rice according to the amount of rice to be cooked. There is a need.

At this time, if you specify the wrong amount of rice to cook and press the operation button, the wrong rice cooking power will be supplied and the rice will not be cooked properly.Furthermore, if you set the built-in timer to the wrong time and operate it, the rice will not boil before it boils. The built-in timer activates, and the electricity necessary for boiling is not supplied, so the rice continues to cook without boiling, and the rice cannot be cooked properly.

In addition, the boiling set time varies depending on disturbance factors such as variations in water temperature, room temperature, and heater power, so it is difficult to determine the appropriate set time, making these operations complicated,
There were problems such as incorrect operation.

The present invention is based on the above considerations, and a temperature detector is installed on the mounting plate near the steam hole of the lid, and the temperature rise near the steam hole is detected and inputted to a microcomputer, which calculates the temperature by performing arithmetic processing. The amount of rice to be cooked is searched based on the temperature gradient, the amount of rice to be cooked is automatically supplied to the heating element according to the amount of rice to be cooked without pressing the operation button to specify the amount of rice to be cooked, and the temperature that changes suddenly during boiling is detected. To provide an electric rice cooker which automatically supplies to a heating element the power required to continue boiling rice by inputting it into a microcomputer and without setting a timer.

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

In Fig. 1, 1 is an outer frame, 2 is an inner frame, 3 is a heating element, 4 is a heating plate, and a heat-responsive switch 5 that can be freely retracted and retracted is provided in the center, and a lever 6 that interlocks with the switch 5 is provided for cooking rice. Open and close switch 7.

The heat-responsive switch 5 operates when the rice cooking end temperature is reached, and is of a type that does not automatically return.

An inner pot 8 for storing rice and water is set on the heating plate 4, and is sealed by a removable inner pot 110 located inside the lid 9.

The lid 9 is provided with a steam hole 11 through which the inner pot 8 vents to the outside,
When the rice begins to boil during cooking, the steam in the inner pot 8 escapes to the outside world through the steam holes 11 as shown by the arrows in FIG. 1 through the gaps.

Reference numeral 12 denotes a rice cooking amount sensor, which is installed near the steam hole 11 in close contact with a mounting plate 14 on the back side of the lid 9, and its output is input to a control device 13.

This position is the position where the boiling time according to the amount of rice to be cooked can be detected most sensitively.

An example of the configuration of the control device 13, as shown in FIG. 2, consists of a microcomputer 17 and its peripheral circuits.

The microcomputer 17 shown here is an arithmetic logic circuit R.
AM (random access memory),
Consists of ROM (read only memory), various registers, oscillators, etc.
It shows a so-called one-chip microcomputer.

The programs necessary for automatic rice cooking are processed and copied onto the ROM in the microcomputer 17 using a mask process.

The rice cooking amount sensor 12 is encoded by a D/A converter 18 and input to the microcomputer 17.

For example, a 4-bit binary number is output from the microcomputer 17, and a comparison circuit in the D/A converter 18 converts the 4-bit binary code into an analog value using a weighted resistor, and a value from the rice cooking amount sensor 12. The microcomputer 17 reads the temperature data from the rice cooking amount sensor 12 equivalently by comparing it with the analog quantity to determine what kind of binary number it is.

When you press the button at the bottom of the outer frame 1 and lower the lever 6, the rice cooking switch 7 closes, and the chattering prevention circuit 19 and resistor 20 close.
A signal at the L19 level is input to the microcomputer 17 through the circuit, and the rice cooking sequence begins.

A series circuit of the heating element 4 of the AC power supply 21 and the bidirectional thyristor 22 is connected, and the gate current of the bidirectional thyristor 22 is configured such that a gate current flows from the DC power supply 23 through the resistor 24 and the light receiving part of the photocoupler 25. be.

By driving the rice cooking power control signal from the microcomputer 17 through the driver 26 and causing a current to flow through the light emitting part resistor 27 of the photocoupler 25, the light receiving part of the photocoupler 25 operates, and the gate current is applied to the DC power supply 23.
The bidirectional thyristor 22 is turned on.

This rice cooking control signal is activated by the heat-responsive switch 5, which outputs an "off" signal when the rice cooking switch 7 whose contacts operate in the open state and the microcomputer 17 determine that the rice cooking is complete. The driving of the thyristor 22 is stopped, and the supply of rice cooking power to the heating element 3 is stopped.

Also, when the rice cooking amount sensor 12 and the microcomputer 17 determine the amount of rice to be cooked and the timing to start boiling, the rice cooking control signal is turned on so that the electric power is commensurate with the amount of rice to be cooked.
The bidirectional thyristor 22 is driven to supply appropriate power to the heating element 3 by changing the energization ratio of "off" and intermittent energization.

Next, the structure configured as described above and the operation of its circuit will be explained.

When rice 15 and water 16 are put into the inner pot 8 and the button under the outer frame 1 is pressed to lower the lever 6, the rice cooking switch 7 is closed and the rice cooking sequence is started.

That is, rice cooking is started according to the procedure of the automatic rice cooking program stored in the ROM in the microcomputer 17.

First, constant power is supplied to the heating element 3 regardless of the amount of rice cooked.

For example, as shown in FIG. 3, the microcomputer 17 outputs a rice cooking control signal that sets the value to the maximum electric power WA.

The mounting plate 14 temperature Ts near the steam hole 11, the rice temperature TK, and the inner pot bottom temperature TM are as shown in Fig. 3 A to C when the rice cooking amount A and B are determined.
, C (A>B>C) each shows a different temperature rise.

The total amount of cooked rice B will be explained.

A program in the ROM stores the data of the temperature L of the mounting plate 14 near the steam vent 11 detected by the rice cooking amount sensor 12 in the RAM area of the microcomputer 17 when a certain amount of time has elapsed since the start of rice cooking. .

Furthermore, when time t has elapsed, the data of the temperature T, =■' of the mounting plate 14 near the steam vent 11 is similarly stored in the RAM area, and at the same time, the program stores Ts=b, L=b.
A routine is entered to perform arithmetic processing to obtain the temperature ΔT b'-b and the gradient A t''' t2-tl based on the data of ', and the results are calculated.

The correlation between the amount of rice cooked and the amount of rice cooked is determined in advance, and the optimum power at that time is set.

For example, the amount of rice to be cooked is divided into three levels, A, B, and C, as shown in Table 1, and fixed in the program in the ROM.

ΔT Therefore, by searching from the value of Te calculated at the time of cherry blossoms and the fixed program above, the microcomputer 17 immediately determines the amount of rice to be cooked from A to C, and switches to the rice cooking power W8 corresponding to ■. A rice cooking control signal is output from the microcomputer 17, and as shown in FIG.
The rice cooking power changes to W8.

Continuing to receive heat from the heating element 3, the temperature T5 of the mounting plate 14 in the vicinity of the steam hole 11 rises, and rises rapidly just before boiling.

When the temperature reaches Tsa, the microcomputer 17 passes through the D/A converter 18 and recognizes that the temperature has reached T83.

Thereupon, a rice cooking control signal to switch the rice cooking power is immediately output from the microcomputer 17, and the rice cooking power WB is set at the time point as shown in Figure 3 according to the procedure of the program in the ROM.
'Switch to '.

Furthermore, the rice cooking power W8' necessary to maintain boiling is supplied to the heating element 3, and as shown in Fig. 3, the rice temperature T rises and the water at the bottom of the inner pot 8 disappears, causing the bottom temperature to rise rapidly. At time t7, the heat-responsive switch 5 operates and the contact of the rice cooking switch 7 opens, and a rice cooking end signal is sent to the microcomputer 17.
The microcomputer 17 outputs an "off" signal as a rice cooking control signal in order to immediately recognize that rice cooking is complete and stop power supply to the heating element 3.

Similarly, in the case of rice cooking amount A or C, the rice cooking amount sensor 1
2, the amount of rice to be cooked is automatically recognized by a fixed program, the optimum power is supplied, and then when boiling starts, the power is switched to the one necessary to sustain the boiling.

Table 2 shows an example of a program for processing data on the temperature of the mounting plate 14 in the vicinity of the steam hole 11 using the microcomputer 17.

Programs (1) to (6) in the table above are temperature gradient "1"
From (7) to 0G, the number of cups of rice to be cooked is determined based on the value of Δt 1L, and the maximum Δ is the routine to set the shutoff power. A routine for setting an appropriate boiling sustaining power at the start time of boiling, and steps (13) to (14) are a rice cooking completion routine.

As described above, according to the present invention, the rice cooking amount sensor 12 is installed near the steam hole 11 of the mounting plate 14, and its output is inputted to the microcomputer to supply electric power commensurate with the amount of rice cooked to the heating element. As a result, the user can cook rice properly without having to set any operation buttons, and also accurately determines when to start boiling and supplies the power necessary to sustain boiling, so the user can simply press the button. Just by pressing , the rice cooking program will proceed with proper power supply, making operation easier and eliminating malfunctions.

In addition, since the rice cooking amount and boiling start time can be accurately determined using 121 rice cooking amount sensors, the circuit configuration and structure are simple, and conventional products can be applied as is.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of an electric rice cooker according to an embodiment of the present invention.
Figure 2 is an electric circuit diagram, and Figure 3 is a diagram showing the rice cooking characteristics for explaining the operation.
The graph showing the relationship between the temperature of the mounting plate near the steam vent and time, the graph showing the relationship between cooking power W and time, and the graph showing the relationship between temperature and time at rice temperature TK and inner pot bottom temperature TM. It is a graph. Death...Inner pot, 11...Steam vent, 12...
...Temperature detector, 17...Microcomputer.

Claims (1)

[Scope of utility model registration request] At the initial stage of rice cooking, rice is cooked using electric power corresponding to the amount of rice to be cooked, and after boiling, the rice cooking power is reduced.A temperature detector 12 is installed near the steam hole 11 through which the inner pot 8 vents to the outside. It calculates the temperature gradient per unit time using the temperature as an input signal, measures the amount of rice cooked, and generates a control signal that specifies the power to the heating element in accordance with the amount of rice cooked. An electric rice cooker characterized in that a control signal specifying switching to the power necessary for continuous operation is inputted to a microcomputer 17.