JP4954227B2 - Cooker - Google Patents

Description

The present invention relates to a cooking device that detects a water level in a water tank .

Conventionally, for example, steam generated during rice cooking is led into a container (water tank) containing cooling water and discharged into the cooling water to condense the steam and convert it into water (condensate). A rice cooker equipped with such a steam recovery apparatus is known. At that time, as a technique for detecting the water level in the container, for example, there is one disclosed in Patent Document 1. This technology relates to detection of the remaining amount of ink in an ink tank of an ink jet printer. A triangular prism having an apex angle of 90 degrees is formed on the bottom surface of the ink tank, and a pair of light emitting element and light receiving element are opposed to the prism. The optical sensor which consists of these is provided.
According to this residual ink detection technology, when the ink tank is sufficiently filled with ink, the light emitted from the light emitting element to the prism does not pass through the prism and return to the light receiving element. Is reduced until it stops contacting the surface of the prism, it is reflected by the slope of the prism that becomes the interface with the ink, and this reflected light returns to the light receiving element, so that the remaining ink is reduced by the output of the light receiving element at that time. Can be detected.

Japanese Patent Laying-Open No. 2005-41183 (page 2-3, FIG. 1)

  However, since the technique disclosed in Japanese Patent Laid-Open No. 2004-228620 is ink remaining amount detection, it is only necessary to detect a decrease in output before ink depletion. Therefore, the detection timing may be performed when not operating (before printing). In addition, since the liquid inside the container is a printing ink and contains dyes or pigments and has high viscosity, the amplitude and time constant of the water level fluctuation are small, so the influence on the water level detection operation, that is, the error of the water level detection accuracy is small It is.

On the other hand, in the case of a rice cooker equipped with a steam recovery device, steam is recovered as bubbles in the water tank during cooking, so the water level in the water tank shakes and the water level rises and falls near the water level detection means. There was a problem of causing false detection. The main causes of the water surface fluctuation are that steam is generated as bubbles in the water tank during steam recovery and rises toward the water surface, boiling in the kettle due to electromagnetic induction heating (also called IH heating), fan operation, And IH vibration, user operation (lid opening / closing, switch operation) and the like.
Also, if the user forgets that the water is still in the water tank and starts cooking, the rice cooker may overflow due to excessive water. Connected. In addition, when the user starts cooking rice forgotten that the water tank is empty or contains only less than a predetermined amount of water, that is, lack of water, the water tank is heated by hot steam. There is a risk of damage.

  In view of the problems as described above, the present invention detects the water level even during the rice cooking operation to prevent false detection accompanying a sudden rise in water level, overflow of water due to excessive water, or damage to the water tank due to water shortage. The purpose is that.

A heating cooker according to the present invention has a water tank for storing water, a light emitting means for emitting light by blinking light, and a plurality of light receiving means for transmitting a signal based on the intensity of the received light. Water level detection means for detecting the presence or absence of water at a plurality of predetermined height positions, and determination means for determining the presence or absence of water based on an average value or a moving average value obtained by smoothing the output of the light receiving means And the determination means determines whether or not the water level is abnormal from the water level detected by the water level detection means before the end of the preheating step of rice cooking control, and determines that it is abnormal. When finished, the rice cooking operation is terminated, and after completion of the steaming process of rice cooking control, from the water level of the water tank detected by the water level detection means, it is determined whether the water is full. It is intended to inform that it is water.

  By comprising in this way, even if it is a case where the water surface in a water tank is shaking, a water level can be detected correctly, without producing a misdetection. Further, it is possible to detect in advance that the water tank is excessive or insufficient.

It is a schematic diagram which shows the internal structure of the heating cooker which concerns on Embodiment 1 of this invention. It is a perspective view which shows the tank main-body part of a water tank. It is explanatory drawing for demonstrating the enlarged view of a reflective transmission part, and the principle of a water level detection. It is a block diagram which shows the structure of a water level detection apparatus. It is a figure showing the fluctuation | variation of the optical sensor output when there is a water surface fluctuation. It is the figure which showed the fluctuation | variation of the optical sensor output when there is a water surface fluctuation, and the digital output by signal processing. It is a figure showing the optical sensor output and the digital output when the output is averaged. It is explanatory drawing in the case of performing majority processing with respect to the output of an optical sensor. It is a flowchart of rice cooking operation | movement. It is the figure showing the timing chart of the pot temperature at the time of rice cooking, transition of input electric power, and water level detection. It is a flowchart which shows the procedure of a water level detection. FIG. 10 is a perspective view showing a tank body part of a water tank having a reflection / transmission part in a second embodiment. It is explanatory drawing for demonstrating the principle of the water level detection of the water tank of FIG.

  Hereinafter, a rice cooker will be described as an example of a heating cooker provided with a steam recovery apparatus to which the present invention is applied, with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram showing an internal configuration of a heating cooker (rice cooker) according to Embodiment 1 of the present invention.
A rice cooker 100 according to the first embodiment includes a main body 1 and a lid 2 that is coupled to the main body 1 through a hinge portion (not shown) so as to be freely opened and closed. In the main body 1, a rice cooker 3 in which an object to be heated (for example, rice and water) is put is detachably accommodated. The rice cooker 3 is heated by heating means 4 such as an induction heating coil provided at the bottom of the main body 1 during cooking.

The lid 2 is coupled to the main body 1 via a hinge part (not shown) on the rear side, and an upper lid (outer lid) 5 attached so that the front (front) side is rotated upward, and a rice cooker 3 And an inner lid 6 that is detachably attached to the upper lid 5. Further, a water tank 7 for storing a predetermined amount of water 9 is detachably accommodated on the front side inside the main body 1. A steam conduit 8 for guiding steam generated from the heated object during cooking to the water in the water tank 7 is detachably provided on the water tank 7 and the lid 2. This steam conduit (or steam pipe) 8 is composed of a first steam conduit 8 a and a second steam conduit 8 b which are divided into two so as to contact and separate at the opening / closing surface of the lid 2. One first steam conduit 8a is formed of a substantially U-shaped pipe that is detachably attached to the inner surface of the upper lid 6. An opening 8c at one end opens at the inner lid 6 and an opening at the other end. 8d is configured to be intimately connected to the upper open end 8e of a straight tubular second steam conduit 8b provided in the water tank 7 via a packing (not shown) when the lid 2 is closed. Yes.
The main body 1 is provided with a fan (not shown) for cooling various electronic components.
A lower opening end 8 f of the second steam conduit 8 b opens into the water in the water tank 7. Although detailed illustration of the water tank 7 is omitted, the water tank 7 includes a lid that detachably covers the upper opening of the tank main body and a handle that can be attached to the lid in a tiltable manner. The second steam conduit 8b is integrally formed of resin on the lid of the water tank 7. In addition, the water tank 7 can be inserted into the main body 1 or taken out from the main body 1 with a tiltable handle attached to the lid.

  Further, in the main body 1, an output signal from a water level detection device 11 including an optical sensor that detects the water level 10 in the water tank 7, a control unit that controls energization of the heating unit 4, and a light receiving unit of the water level detection device 11. And a determination control means 12 having a determination unit for determining the presence or absence of water.

FIG. 2 is a perspective view showing the tank main body portion 7a of the water tank 7, and FIG. 3 is an enlarged view of the reflection / transmission portion 13 formed on the side wall surface of the tank main body portion 7a, together with explaining the principle of water level detection. It is explanatory drawing for. FIG. 4 is a block diagram showing the configuration of the water level detection device 11.
The water tank 7 is formed using a light-transmitting material such as polysulfone (PSF), polystyrene, glass, or the like having a total light transmittance of 80% or more based on JIS K7361. Further, a part of the inner surface of one side wall surface of the water tank 7 becomes a reflection / transmission part 13 whose light reflection amount and transmission amount change depending on the presence or absence of water, for example, a triangular prism column (vertical angle 90 °) ( (Hereinafter referred to as a prism column) 13a is integrally formed along the height direction. Note that the optical characteristic portion on which the prism column 13a is formed may be bonded to the tank main body portion 7a formed of a different material by adhesion or thermal fusion.

  The water level detection device 11 includes a plurality (for example, three sets) of optical sensors 15, 16, and 17 arranged at different heights so as to face the prism column 13a. Each of the optical sensors 15, 16, and 17 is disposed at the same height level as the light emitting means 18 that irradiates light toward the prism column 13a and the light emitting unit 18, and according to the amount of light received through the prism column 13a. And a light receiving means 19 for generating a signal.

  Each light emitting means 18 is made of, for example, a light emitting diode, and irradiates near infrared rays having a wavelength of 940 nm toward the prism column 13a. Each light receiving means 19 is composed of, for example, a photodiode, a phototransistor, etc., and the light emitted from the light emitting means 19 is reflected by the prism column 13a. When this reflected light is received, the output of the light receiving means 19 is amplified by the amplifier 20. Then, the signal is input to the control / signal processing circuit 21 of the determination control means 12, and the control / signal processing circuit 21 performs signal processing as will be described later, and then the output signal is inverted from the Low level to the High level. Yes. Thereby, it is possible to detect that the water level 10 has reached the height position of the optical sensor. The water level 10 is displayed on a display 22 such as a liquid crystal provided on the surface of the lid 2.

Here, the operation of the water level detection device 11 will be described with reference to FIG. Since the water level detection operations of the optical sensors 15, 16, and 17 are all the same, the water level detection operation of the lowest optical sensor 15 will be described here. However, the explanation here assumes that there is no shaking of the water surface or when it is small (when calm).
At a certain timing, the light emitting means 18 of the optical sensor 15 irradiates near infrared light having the above wavelength toward the prism column 13 a formed on the inner surface of the water tank 7. When the water level 10 in the water tank 7 does not reach the height level of the optical sensor 15, the incident light emitted from the light emitting means 18 is an optical path as indicated by solid arrows on the two inclined surfaces of the prism column 13a. The light is sequentially refracted and reflected through the light and reflected toward the light receiving means 19. Since this reflected light is received by the light receiving means 19 arranged at the same height level as the light emitting means 18, the output of the light receiving means 19 becomes a high level signal, and the light receiving means 19 determines and controls the high level signal. Output to means 12. Therefore, the determination control means 12 determines that the water level 10 has not reached the lowest level, that is, the water tank 7 is short of water.

  On the other hand, when the water level 10 in the water tank 7 exceeds the height level of the optical sensor 15, the incident light from the light emitting means 18 passes through the prism column 13a as shown by the dotted arrow and is transmitted into the water. Therefore, since the reflected light does not return to the light receiving means 19, the light receiving means 19 inverts the output signal from the High level to the Low level and outputs it to the determination control means 12. Therefore, the determination control means 12 determines that the water level 10 has reached the lowest level, that is, the water tank 7 is not short of water.

In the rice cooker 100 configured as described above, the rice cooker 3 containing a heated object such as rice and water is accommodated in the main body 1, and a predetermined amount of water is put in the water tank 7 to main body 1. When the lid 2 is closed and the rice cooking start switch is operated, the determination control means 12 starts energizing the heating means 4 and heats the object to be heated via the rice cooker 3. Tell.
As the rice cooking operation proceeds, steam is generated from the object to be heated in the rice cooking pot 3. The generated steam is guided into the water tank 7 through the steam conduits (first and second steam conduits 8a and 8b), and discharged into the stored water in the water tank 7. The steam discharged into the water in the water tank 7 rises in the form of bubbles, but is cooled by the water, condensed, and converted into water (condensed).

At that time, as described above, when the steam is collected in the water tank 7, not only the water level rises, but also the water surface shakes. The amount of rise in the water level depends on the amount of cooked rice, but the amount of water collected by one cooked rice is about 50 to 100 mL. For example, when the bottom of the water tank 7 is a rectangle of 20 cm × 5 cm and the area is 100 cm ² , the water level rises by about 0.5 to 1 cm by one cooking rice.
Moreover, when the water surface repeatedly rises and falls at the height at which the water level detecting means is installed, the output voltage of the light receiving means 19 rises and falls according to the movement of the water, so the water level at the time of calming has not yet reached the full water level Nevertheless, it may be falsely detected as full.
Therefore, the output signal from the light receiving means 19 is processed by the control / signal processing circuit 21 as follows.

This output signal processing method will be described with reference to FIGS. FIG. 5 is a diagram showing the fluctuation of the optical sensor output when the water surface shakes. The horizontal axis represents time (sec), and the vertical axis represents the voltage (mV) of the light receiving means 19. The solid line represents the output without water during calm (that is, the output when the water level does not reach the installation height of the water level detection means in the state where there is no water fluctuation), and the dotted line represents the output without water during the water surface fluctuation (that is, the water surface). Shows the output when the water level detection means installation height is raised or lowered. Moreover, the output fluctuation of about 5 seconds is shown.
Thus, when the water surface shakes, the output of the optical sensor fluctuates, so the output is not stable and the actual position of the water surface is unknown.

FIG. 6 is a diagram showing the fluctuation of the optical sensor output and the digital output by signal processing when the water surface is shaken.
As shown in the upper diagram of FIG. 6, a certain threshold value (for example, 60 mV) is set for the waterless output when the water surface is swayed in FIG. 5, and the output signal obtained by cutting with this threshold value is AD converted. 6 is a lower view of FIG.

As shown in FIG. 7, the first method of signal processing is a method of obtaining an average value by smoothing the output signal. FIG. 7 is a diagram (lower diagram) showing the optical sensor output (upper diagram) and the digital output when the output is averaged. That is, after measuring the output Von of the light receiving means 19 within a predetermined time with respect to the output when the water surface is shaken as shown in FIG. 5, and binarizing as shown in FIG. Then, the average value is calculated, and based on this average value, the presence / absence of water is determined. By outputting the result as shown in FIG. 7, output fluctuation due to water surface fluctuation is suppressed and the output is stabilized.
According to the first method, it is possible to reduce the sudden fluctuation caused by the water surface fluctuation, stabilize the output by a relatively simple method, and improve the reliability of the water level detection.

The second method is a method of obtaining a moving average value as an output averaging process. That is, as shown in FIG. 5, the average value of the output Von of the light receiving means 19 within a predetermined time is sequentially calculated with respect to the output at the time of the water surface fluctuation, and finally the discrimination process is performed. The result is shown in FIG. Output (although there is actually a slight refraction, as shown in FIG. 7), the output fluctuation due to the water surface fluctuation is suppressed and the output is stabilized.
According to the second method, it is possible to detect a change in the average value in a short period of time more accurately than the first method, and more accurately cope with a sudden change due to water surface fluctuation. Can do.

In the third method, instead of the above-described averaging process, as shown in FIG. 8, a majority decision is made based on the comparison result between the odd number of output voltages and the discrimination threshold. That is, as shown in FIG. 5, the number of times of performing the discrimination process by measuring the output Von of the light receiving means 19 every predetermined time is repeated (2N + 1) times (N is an arbitrary natural number) with respect to the output at the time of water surface shaking. The output is stabilized by outputting the final discrimination result by majority decision of the discrimination result as shown in FIG. In addition, since it is a majority decision, it is an odd number of times.
In the case of FIG. 8, since the number of appearances equal to or greater than the determination threshold is 10 and the number of appearances less than the determination threshold is 5, the determination result is determined to be no water.
According to the third method, since it is only necessary to count the number of appearances of the output voltage that is equal to or greater than the discrimination threshold and less than the discrimination threshold, it is possible to easily detect the presence or absence of water due to a sudden fluctuation due to water surface fluctuation. .

Next, the procedure of the rice cooking operation of this rice cooker 100 will be described with reference to the flowchart of FIG. In the description of FIG. 9, the heating of the heating means 4 is abbreviated as IH heating.
First, immediately after the start of cooking, the water level of the water tank 7 is detected (S1). It is determined whether the water level is normal (S2), and if normal, IH heating of the heating means 4 is performed and the preheating step T1 is entered (S3). If the water level is abnormal, rice cooking is stopped (S10). In this case, since the water tank 7 is short of water (because there is less water than the predetermined amount) or excessive water (too much water than the predetermined amount), this is indicated by either a voice message, buzzer, flashing display, etc. Both are alert | reported to a user (S11), and rice cooking operation | movement is complete | finished. Prior to the end of the preheating step T1, the water level is detected again (S4). Then, it is determined whether the water level is normal (S5). When the water level is normal and the preheating step T1 is not completed, the process returns to S3. When a water level is abnormal, it transfers to said S10 and S11, and rice cooking operation | movement is complete | finished. And only when the water level is normal and the preheating step T1 is completed, the IH heating is strengthened and the process proceeds to the rice cooking step T2 (S6). After the completion of the rice cooking process T2, the process proceeds to the steaming process T3 (S7). And after steaming process T3 is complete | finished, a water level detection is performed again (S8). It is determined whether the water level is normal (S9). If normal, the rice cooking operation is terminated. When the water level is abnormal, it is informed that the water tank 7 is full after the completion of cooking (S12). This full water notification can prevent excessive water at the start of the next cooking.

  FIG. 10 is a diagram showing a kettle temperature during cooking, transition of input power, and a timing chart of water level detection. As apparent from FIGS. 10 and 9, the water level detection is optimally performed when the water surface in the water tank 7 is small, that is, during the preheating step T1 and the steaming step T3. Even when there is such a shaking of the water surface, it can be detected by the above-described first to third methods. Specifically, it is as follows.

(1) At the time of maximum power input (or when the thermal power is maximized) in the rice cooking process T2 of rice cooking control, a large amount of steam is generated due to boiling of the object to be heated and the water surface shake is the largest period. In order to avoid the output fluctuation of the light receiving means 19 of the optical sensor due to the water level, the water level detection is not executed during this period. Thereby, the output of the water level detection apparatus 11 can be stabilized.
(2) As shown in FIG. 10, at the time of maximum power input in the rice cooking process T2 of rice cooking control, the pulse-like output measured when the water level approaches the position of the full water level detecting means (light sensor 17). In the full water level detection means, the number of pulses is counted within a predetermined time, and when the number of pulses exceeds N times, the approach of the water surface is predicted to prevent overflow. In addition, the user is notified that the water surface has approached the full water level so that the water in the water tank 7 is discarded at the end of this cooking. Further, instead of counting the number of pulses, the amplitude of the water surface fluctuation may be measured and an amplitude determination threshold value may be provided.
(3) The water level is detected after the rice cooking start button is pressed, and then the fan and IH heating are started. Because the water level is small, the water level can be detected accurately.
(4) After the end of cooking rice, the water level is detected when the fan is stopped and the IH heating is stopped.
(5) During the rice cooking operation, the water level is detected at the timing of 1) IH off, 2) fan off, or 3) IH and fan off.
(6) When the water level is detected after the IH is turned off, the water level is detected after a predetermined time has elapsed after the IH is turned off. This is because even after the IH heating is turned off, steam is released into the water in the water tank 7 as bubbles for a while after the residual heat, and the water level fluctuation continues. Therefore, the water level is detected after the water level fluctuation has subsided. This is to do accurately.

FIG. 11 is a flowchart showing the procedure of water level detection, which will be described below. In the following description, the output signals of the optical sensors 15, 16, and 17 that are water level detection means are “sensor signal L”, “sensor signal M”, and “sensor signal H”, respectively.
When the water level detection operation is started, the sensor signal L of the lowest optical sensor 15 is input to the control / signal processing circuit 21 shown in FIG. 4 (S21). As described above, the sensor signal L determines the presence or absence of water based on an average value, a moving average value, or a majority decision, and the determination threshold is represented by “T” below. Similarly, the determination threshold value of the sensor signal M and the sensor signal H is represented by “T”.
It is determined whether the output of the optical sensor 15 is smaller than the determination threshold T (S22). If No, the water level in the water tank 7 has not reached the lowest level, so it is determined that water is insufficient (S28), and the water level is An abnormality is output (notified) (S31), and the water level detection is terminated. If the determination result is Yes in S22, the sensor signal M of the optical sensor 16 at the intermediate position is input (S23).
It is determined whether the output of the optical sensor 16 is greater than the determination threshold T (S24). If No, the water in the water tank 7 is determined to be excessive because the amount of water is greater than a predetermined amount (S29). It outputs (notifies) that the water level is abnormal (S31), and ends the water level detection. Conversely, if Yes, the sensor signal H of the next highest optical sensor 17 is input (S25). Then, it is determined whether the output of the optical sensor 17 is larger than the discrimination threshold T (S26), and if No, it indicates that the water surface is close to the full water level. Outputting (notifying) (S31), the water level detection is terminated. On the other hand, if Yes, the water level is normal, so that the water level is normal is output (S27), and the water level detection is terminated.

As described above, according to the first embodiment, the presence or absence of water is determined based on the average value or the moving average value obtained by smoothing the output signal of each light receiving means 19 of the water level detection device 11. Therefore, even if it is a case where the water surface in the water tank 7 is shaking by the rice cooking process etc., a water level can be detected correctly, without producing a false detection. Moreover, the presence or absence of water can also be determined by a majority decision based on the comparison result of the number of outputs of each light receiving means 19 in an odd number of times. Similarly, when the water surface in the water tank 7 is shaking in the rice cooking process or the like. Even if there is, it is possible to accurately detect the water level without causing erroneous detection.
In addition, it is possible to detect in advance that the water tank 7 is excessively water shortage or water shortage, and it is possible to prevent water overflow and water shortage in advance.

Embodiment 2. FIG.
FIG. 12 is a perspective view of the tank body 7 a showing the reflection / transmission part 13 formed on the side wall surface of the water tank 7 in the second embodiment. FIG. 13 is an explanatory diagram for explaining the principle of water level detection of the water tank 7 having the reflection / transmission part 13.
The reflection / transmission part 13 is formed by forming a concave groove part 13b having inclined surfaces on both the inner and outer sides along the height direction on a part of the outer surface of one side wall surface of the water tank 7. is there. The angles of the inner and outer inclined surfaces 13c and 13d or 13e and 13f may be the same or different.

  The light emitted from the light emitting means 18 passes through the optical path indicated by the solid line arrow, is refracted and transmitted by the incident side inclined surface 13c, enters the tank wall surface, and reaches the incident side reflection / transmission surface 13d. When the water level 10 does not reach the height level of the light receiving means 19, the incident light is reflected by the incident side inclined surface 13d and travels along the tank wall surface along the tank wall surface as indicated by the solid line arrow. Then, the light is refracted and reflected by the reflection-side inclined surface 13e, further passes through the reflection-side inclined surface 13f and travels toward the light receiving means 19, and the light receiving means 19 receives the reflected light. On the contrary, when the water level 10 reaches the height level of the light receiving means 19, the incident light incident from the incident side inclined surface 13c is not reflected by the incident side inclined surface 13d as shown by the broken line arrow. Since the light passes through the water in the water tank 7, the reflected light does not return to the light receiving means 19, so that it is possible to detect that the water level 10 has reached the height level of the light receiving means 19 or higher.

  According to the second embodiment, the same effects as those of the first embodiment can be obtained, and the concave groove 13b is formed as the reflection / transmission portion 13. Therefore, the thickness of the water tank 7 is substantially the same. Since it can be molded, there is an effect that deformation such as distortion due to resin molding hardly occurs.

  In the first and second embodiments, each optical sensor receives a single incident light from the light emitting means per time by the light receiving means and outputs a signal, and this signal processing is performed for a predetermined time (for example, about 5 seconds). Although it was shown that it was repeated at intervals and then smoothed, etc., single incident light per time may be affected by noise, and if noise occurs, accurate signal output is obtained. It will not be possible. Therefore, a plurality of outputs are output from the light emitting means in a short time, such as a flash, and a plurality of incident lights are received by the light receiving means and averaged to output a signal for a predetermined time (one time). For example, it may be repeated at intervals of about 5 seconds. Thereby, the influence of noise can be reduced.

  As is apparent from the above description, the present invention is not limited to a rice cooker as long as it is a heating cooker provided with a steam recovery device. The heating means is not limited to the electromagnetic induction method, but may be an electric heater, a combination of the electromagnetic induction method and the heater method, or a gas using a heat source.

  DESCRIPTION OF SYMBOLS 1 Main body, 2 Lid body, 3 Rice cooker, 4 Heating means, 5 Upper lid, 6 Inner lid, 7 Water tank, 8 Steam conduit, 9 Water, 10 Water level, 11 Water level detection apparatus, 12 Judgment control means, 13 Reflection transmission Part, 13a prism column, 13b groove part, 15, 16, 17 light sensor, 18 light emitting means, 19 light receiving means, 20 amplifier, 21 control / signal processing circuit, 22 display, 100 rice cooker.

Claims (7)

A water tank for storing water;
A water level for detecting the presence or absence of water at a plurality of predetermined height positions of the water tank, having a plurality of sets of light emitting means for emitting light by blinking and light receiving means for transmitting a signal based on the intensity of the received light Detection means;
Determination means for determining the presence or absence of water based on an average value or a moving average value obtained by smoothing the output of the light receiving means,
The determination means includes
From the water level of the water tank detected by the water level detection means before the end of the preheating process of rice cooking control, it is determined whether the water level is abnormal, and when it is determined abnormal, the rice cooking operation is terminated.
From the water level of the water tank detected by the water level detection means after completion of the steaming process of rice cooking control, it is determined whether or not the water tank is full. A cooking device characterized by. A water tank for storing water;
A water level for detecting the presence or absence of water at a plurality of predetermined height positions of the water tank, having a plurality of sets of light emitting means for emitting light by blinking and light receiving means for transmitting a signal based on the intensity of the received light Detection means;
Provided by an odd number of times the comparison result of the majority of the determination threshold value at the output of the light receiving means, a determination means for performing determination of the presence or absence of water, and
The determination means includes
From the water level of the water tank detected by the water level detection means before the end of the preheating process of rice cooking control, it is determined whether the water level is abnormal, and when it is determined abnormal, the rice cooking operation is terminated.
From the water level of the water tank detected by the water level detection means after completion of the steaming process of rice cooking control, it is determined whether or not the water tank is full. A cooking device characterized by. The cooking device according to claim 1 or 2 , wherein the output of the light receiving means is obtained by averaging the amounts of light emitted from the light emitting means . The determination means includes
The full water level is predicted from the water level of the water tank detected by the water level detection means during the maximum power input period in the rice cooking process of rice cooking control, and the prediction result is notified. The heating cooker as described in any one of. The determination means includes
It is determined whether or not a water surface exists at each position of the light receiving means by measuring the outputs of the plurality of light receiving means for a certain period of time and comparing the average value calculated from the measured values with a discrimination threshold. The heating cooker as described in any one of Claims 1-4 characterized by the above-mentioned. The determination means includes
It is determined whether or not there is a water surface at each position of the light receiving means by measuring the outputs of the plurality of light receiving means for a certain period of time and comparing the moving average value calculated from the measured values with a discrimination threshold. The heating cooker according to any one of claims 1 to 4, wherein: The determination means includes
The output of each of the plurality of light receiving means is measured at regular time intervals, and it is determined whether or not a water surface exists at each position of the light receiving means by a majority decision based on the result of repeatedly comparing the output and the discrimination threshold value an odd number of times. The heating cooker according to claim 2 or 3 or 4 depending on claim 2.

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