JPH0464684B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is applicable to rice cookers used in general households.
The present invention relates to a rice cooker equipped with a timer device for setting an operation start time.

Conventional configuration and its problems Traditionally, electric rice cookers used in general households are equipped with a timer device such as a motor timer, and if rice and water are set the night before, they will automatically start cooking the next morning. There was something to do. The conventional timer-equipped rice cooker as described above will be described below with reference to the drawings.

FIG. 1 shows an electric circuit of a conventional timer-equipped rice cooker. In FIG. 1, reference numeral 1 denotes a timer device such as a motor timer. When a user sets a time, a contact 2 opens, and when the set time elapses, a contact 2 closes.
Reference numeral 3 denotes an electric heating element, which generates heat when energized and performs a heating operation. 4 is a thermo switch for detecting the completion of rice cooking, which automatically turns off when the rice cooking is completed. 5 and 6 are resistors and neon tubes connected in series to indicate timer operation. 7 and 8 are resistors and neon tubes that display the rice cooking operation.

9 is a temperature fuse for preventing excessive temperature rise, and 10 is a power plug.

The operation of the timer-equipped rice cooker configured as above will be explained below.

When rice and water are set in a pot, a power plug 10 is connected to a power source, and a thermoswitch 4 is turned on, rice cooking starts if the timer device 1 is set to 0 time. If you now set the timer device 1 to a predetermined time,
Since the contact point 2 is opened, a current flows through the path of the electric heating element 3, the timer device 1, and the thermoswitch 4, the timer motor etc. are operated, and the neon lamp 6 for indicating the timer operation is lit. When the set time has elapsed, the contact 2 closes and the electric heating element 3 is energized to start heating. Thereafter, when the rice is cooked and the water evaporates and the temperature rises, the thermoswitch 4 shuts off.

However, the above configuration has the following drawbacks.

First, rice and water are left in a pot without being heated for a certain period of time using timer device 1, but if water is added instead of hot water, the rice will absorb water significantly before starting cooking. When I cooked the rice after this, I ended up with soggy rice. In Figure 2,
The water absorption characteristics of rice are shown using water temperature as a parameter.When the water temperature is 60℃, it absorbs water more significantly after 20 minutes than at other water temperatures, and after 100 minutes, the water absorption rate is 60%. The maximum time that 60°C hot water and rice can coexist is 2.
It can be said that it takes about 30 minutes. Therefore, with a rice cooker equipped with a timer, there is a problem that it cannot be set for a longer time than this, and even if it is set, the finished rice will be stale.

Next, when the room temperature is high, such as during the summer,
If you put a certain amount of water into a pot with rice, over a long period of time, the rice will change in quality, producing an odor, and even if you cook it afterwards, the finished rice will have an odor. When the room temperature is approximately 30°C, the above-mentioned problem occurs when the time exceeds 6 hours.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention automatically shortens the timer setting time when the temperature inside the pot or the room temperature is high, thereby preventing the rice from rapidly reabsorbing water or deteriorating the quality of the rice. This is related to a rice cooker that can be used for cooking.

Structure of the Invention In order to achieve the above object, the rice cooker of the present invention includes a detection device that detects the temperature inside the pot or room temperature, and a timer device that starts the rice cooking operation when a set time arbitrarily set by the user has elapsed. , the configuration includes a control circuit that shortens the set time of the timer device according to the temperature detected by the detection device. By doing this, when hot water and rice are placed in the pot, the timer will automatically shorten the setting time when the room temperature is high in summer, preventing significant water absorption and deterioration of the rice. This is to be prevented.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 3 is a block diagram showing the electrical configuration of the timer-equipped rice cooker according to the first embodiment of the present invention.

In FIG. 3, 11 is a temperature detection device inside the pot;
12 is a room temperature detection device, each of which detects the water temperature in the pot,
Detects room temperature by replacing it with an electrical signal. 13
1 is a control circuit of the timer device 14, and 14 is the timer device. The setting time of the timer device 14 is shortened by the control circuit 13. Reference numeral 15 denotes an electrical contact of the timer device 14. During the timer setting, the contact 15b and the contact 15c are connected, and at the zero time period, the contact 15a and the contact 15c are connected. 16 is a thermo switch for detecting the end of rice cooking, which automatically shuts off when the rice cooking is completed.

17 is an electric heating element for heating; 18 and 19 are resistors and neon lamps connected in series for displaying rice cooking; 20 and 21 are resistors and neon lamps for displaying timer operation; 22 is a DC power source for the circuit; 23 24 indicates a temperature fuse for preventing excessive temperature rise, and 24 indicates a power plug.

The operation of the timer-equipped rice cooker configured as above will be described below.

First, put a predetermined amount of rice and water into a pot, plug in the power plug 24, and turn on the thermoswitch 16. If you do not want to operate the timer now, place the timer device 14 in the 0 time period, and the contacts 15a and 1
5c, the electric heating element 17 is energized and rice cooking starts immediately.

Also, when operating the timer, timer device 1
4 to a predetermined time. At this time, contact 15
b and the contact 15c, the neon lamp 21 for timer operation display lights up, and the electric heating element 17
is not energized.

While the timer is operating, the temperature detection device 11 in the pan,
If any of the room temperature detection devices 12 detects that the set temperature has been exceeded and an output is generated,
The timer set time input to the control circuit 13 of the timer device 14 is shortened. In this case, since the pot internal temperature detection device 11 is set at about 50° C., the setting time of the timer is shortened when significant water absorption occurs as shown in FIG. Since the room temperature detection device 12 is set to a temperature between 25° C. and above and 30° C. and below, the setting time of the timer can be shortened when the room temperature becomes high in summer.

When the timer operation ends and reaches the 0th period, contact 1
5a and contact 15c are connected to energize the electric heating element 17 and start cooking rice.

FIG. 4 is an electric circuit diagram of a rice cooker with a timer according to a second embodiment when applied to a jar rice cooker.

In FIG. 4, 30 is a negative characteristic thermistor resistor 31, 3 provided to detect the temperature inside the pot.
2 and 33 constitute a bridge circuit, and the output of this bridge circuit is connected to the input terminal of a voltage comparator 34. The output of the voltage comparator 34 will be at a low level if the temperature inside the pot is lower than the set value, and will be at a high level if it is higher. Voltage comparator 34
The output of is connected to NPN transistor 35 and resistor 36.
connected via. 37 is the base resistance, 3
8 is a resistor for supplying a base current to the transistor 35, and the transistor 35 is turned on and off according to the output of the voltage comparator 34. 39 is a winding of a reed relay, and when the transistor 35 is turned on, the winding 39 is energized, and the contact 40 of the reed relay is turned on.
will open.

Reference numeral 41 denotes a negative characteristic thermistor provided for detecting room temperature, which together with resistors 42, 43a, and 44 constitutes a bridge circuit, and the output of the bridge circuit is connected to the input terminal of a voltage comparator 45.

The output of the voltage comparator 45 will be at a low level if the room temperature is lower than the set value, and will be at a high level if the room temperature is higher than the set value. 46 is the winding of the reed relay, and the voltage comparator 4
5 is energized to close contact 79 when it is at a low level. The output of the voltage comparator 45 is
It is connected to an NPN transistor 48 and is turned on and off according to the output of the voltage comparator 45. 49
is the base resistance.

50, 51, and 52 are variable resistors and capacitors connected in series to set the operating frequency of the oscillation circuit.The oscillation frequency is changed by the variable resistor 50, and the capacitor 52 is connected by the contact 40.
is short-circuited, the oscillation frequency increases.

53 is a timer circuit, which divides the oscillation frequency sequentially using a flip-flop to obtain a timer set time, and when the set time elapses, the relay coil 5
4 is energized. 55 is a diode for absorbing back electromotive force generated in the coil.

Reference numeral 56 denotes a switch that operates in conjunction with the variable resistor 50, and when the timer is set and an immediate start is desired, when the switch 56 is turned on, the relay coil 54 is energized.

57 is a contact driven by the relay coil 54, and during timer setting, contact 57b and contact 57c
is connected and the timer reaches 0 time period, contact 57
a and contact 57c are connected. 58 is a thermo switch for detecting the completion of rice cooking, and when cooking rice, contact 5
8a and contact 58c are connected,
When rice cooking is completed, contacts 58b and 58c are automatically connected.
Switch to connection with. 59 is an electric heating element for heating, and a transistor 62 having a base resistor 61 via a resistor 60 and a transistor 65 having a base resistor 64 via a resistor 63 have their base terminals connected to the contact 58b of the thermoswitch 58. It is connected. Therefore, when the rice cooking is finished and the thermo switch 58 is switched between the contact 58b and the contact 58c, the transistor 62 is turned on and the timer circuit 53 is reset, and the transistor 65 is turned on.
is also turned on, energizing the relay coil 54, and contact 57
is maintained at the connection between contact 57a and contact 57c.

67 and 68 are resistors and neon lamps connected in series to display rice cooking operation, and 69 and 70 are resistors and neon lamps connected in series to display timer operation, each of which is turned on during rice cooking operation or timer operation. It is a light.

71 and 72 are diodes and capacitors connected in series, which function to generate DC power for the circuit.

Reference numerals 73 and 74 indicate electric heating elements provided at the top and side of the jar rice cooker, which perform heating operations by being energized during the heat-keeping operation. 75 and 76 are resistors and neon lamps connected in series to indicate heat retention operation, 77
is a 2-way 3-terminal thyristor with an electric heating element 59,
73 and 74 in series, and the electric heating elements 59 and 7 are turned on and off by the two-way three-terminal thyristor 77.
3,74 is controlled. 78 is a gate resistor, and 79 is a contact of the reed relay 46. During the heat retention operation, the thermoswitch 58 has contacts 58b and 58c connected, and is connected to a resistor 43b in parallel with the resistor 43a. Therefore, the negative characteristic thermistor 41, the resistors 42, 43a and 43b, 4
The temperature set in step 4 is higher than the setting during rice cooking, and is suitable for the operating temperature of about 70°C. The temperature inside the pot is detected by the negative characteristic thermistor 41 during warming as well as during cooking, and the voltage comparator 45 thereby drives the reed relay 46 to turn on and off the contact 79 of the gate circuit of the 2-way 3-terminal thyristor 77. , electric heating elements 59, 73, 7
4 is controlled by a two-way three-terminal thyristor 77 to perform a heat-retaining operation.

80 is a temperature fuse for preventing excessive rise, 81 is a power switch, and 82 is a power plug.

FIG. 5 is a sectional view of the main body to which the second embodiment is applied, showing the arrangement of each component.

82 is the main body of the jar rice cooker, and a switch box 84 is provided on the front of this main body 83.
Reference numeral 85 denotes a printed board installed in the switch box 84, on which the negative characteristic thermistor 30, variable resistor 50, and neon lamp 68 shown in FIG.
etc. are installed. A knob 86 is attached to the variable resistor 50 so that it can be operated from the outside.

Reference numeral 87 denotes a pot housed inside the main body, which is placed on top of the electric heating element 66 in FIG. It is being

Electric heating elements 73 and 74 for keeping warm are arranged at the top and side of the pot 87.

Reference numeral 88 denotes a heat sensitive part of a thermoswitch for detecting the completion of rice cooking, which is placed in contact with the bottom of the pot 87, and the movement of this heat sensitive part is transmitted by a lever 89 to operate the switch 56. 90 is a lever section for manual input.

FIG. 6 is a block diagram of the timer circuit.
In Fig. 6, 90 is an oscillation circuit, and resistor 5
0, oscillates at a frequency determined by capacitors 51 and 52. 91, 92, . . . , 93 are flip-flops that sequentially divide the oscillation frequency. 9
4 is a power supply regulator that stabilizes the DC voltage supplied to each circuit. Reference numeral 95 indicates an output circuit, and reference numeral 96 indicates a reset circuit. With this configuration, a predetermined set time can be obtained, and the set time can be set using the variable resistor 50.
Furthermore, when the contact 40 opens, the oscillation frequency increases and the set time is shortened.

The operation of the timer-equipped rice cooker configured as above will be explained below.

First, put rice and water in a pot 87, connect the power plug 82 to the power source, and turn on the power switch 81. If the timer does not work, use the variable resistor 50
When the switch is set to the 0 time position, the contact 56 is closed and the relay coil 54 is energized, so the contact 57
When the contacts 57a and 57c are connected and the thermo switch 58 is turned on, the electric heating element 59 is energized to start cooking rice.

Next, in the case of timer operation, the variable resistor 50
is set at a predetermined time and the thermo switch 58 is turned on, the contact 56 is in the open state,
Since the output terminal c of the timer circuit 53 is also off, the relay coil 54 is not energized and the contact 57
In this case, the contacts 57b and 57c are connected, the neon lamp 70 for displaying the timer operation is lit, and this state continues until a predetermined period of time has elapsed.

During this time, if the negative characteristic thermistor 41, which corresponds to a device that detects the temperature inside the pot, or the negative characteristic thermistor 30, which corresponds to a device that detects room temperature, detects that these temperatures are higher than the set value, the room temperature is changed. If using a detection device, contact 4
0 is opened, the oscillation frequency of the capacitor 52 increases, and the timer setting time is automatically shortened.

Further, in the case of using a device for detecting the temperature inside the pot, the transistor 48 is turned on and the relay coil 54 is energized to immediately start cooking rice.

As described above, when rice cooking starts and then ends, the thermoswitch 58 automatically shuts off, contacts 58b and 58c are connected, the transistor 62 resets the timer circuit, and the transistor 65 resets the timer circuit. Relay coil 5
4 is energized and the contact 57 is connected to the contact 57a and the contact 57.
c is connected. Furthermore, a resistor 43b and a resistor 43a are connected in parallel to the bridge circuit of the temperature detection circuit inside the pot, so that the temperature can be switched to the control temperature for keeping warm.

In this way, after rice cooking is completed, the contact 79 inserted into the gate circuit of the 2-way 3-terminal thyristor is
The electric heating element 5 is turned on and off by the temperature detection device inside the pot.
9, 73, and 74 can be controlled to maintain heat.

Therefore, by providing at least one of a pot internal temperature detecting device and a room temperature detecting device, and having a timer device that automatically shortens the setting time based on the output of the detecting device, the timer can be set quickly. This prevents the rice from deteriorating due to hot water or high room temperature, which could cause the rice to fail to cook.Furthermore, the pot temperature detection device can also be used for control purposes during the warming operation. Therefore, it is more effective.

Effects of the Invention As described above, the present invention provides a temperature detection device in a pot,
or at least one room temperature detection device;
It is equipped with a timer device whose set time is controlled by the output of these detection devices, and the timer is automatically set when hot water and rice are put in the pot, or when the room temperature is high in summer. Since the rice cooker can operate in such a way as to shorten the cooking time, it has great practical effects in that it can prevent significant water absorption and deterioration of the rice and provide a rice cooker that does not fail in cooking.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram of a conventional rice cooker with a timer, Fig. 2 is a graph showing how the water absorption rate of rice changes over time depending on water temperature, and Fig. 3 is a diagram of the first embodiment of the present invention. 4 is an electric circuit diagram showing the second embodiment of the present invention, and FIG. 5 is a block diagram showing the second embodiment of the present invention.
FIG. 6 is a sectional view of a main part of a rice cooker to which the second embodiment is applied, and FIG. 6 is a block diagram of a timer circuit in the second embodiment. DESCRIPTION OF SYMBOLS 11... Temperature detection device in a pot, 12... Room temperature detection device, 13... Control circuit, 14... Timer device, 30, 41... Negative characteristic thermistor.

Claims (1)

[Claims] 1. A detection device that detects the temperature inside the pot or room temperature, a timer device that starts the rice cooking operation after a set time that is arbitrarily set by the user, and a timer device that shortens the setting time of the timer device according to the temperature detected by the detection device. A rice cooker equipped with a control circuit.