Heating cooker

Abstract

This heating cooker comprises: a heating chamber that accommodates therein food; a heating unit that heats the food accommodated in the heating chamber; a radiation unit that radiates, toward the heating chamber, radiation light of a first wavelength exhibiting relatively high absorbance in water and radiation light of a second wavelength exhibiting relatively low absorbance in water; a light reception unit that receives the reflected light of the first wavelength and the reflected light of the second wavelength reflected in the heating chamber; and a control unit that controls the heating unit on the basis of a change in light quantity in association with the lapse of time of each of the reflected light of the first wavelength and the reflected light of the second wavelength received by the light reception unit.

Description

heating cooker

[0001] The present disclosure relates to a cooking device for heating food.

[0002] BACKGROUND ART Conventionally, cooking devices have been known in which food is placed in a heating chamber and cooked using microwaves or the like (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2020-3074

[0004] However, as food is heated in a cooking appliance, the moisture inside the food evaporates, causing changes in the food's shape, color, hardness, etc. The changes in food state vary depending on the type and individual food, so it is desirable to heat each food in a way that is more appropriate for its state.

[0005] Therefore, an object of the present disclosure is to solve the above problems and to provide a cooking device that can heat food in a more appropriate manner.

[0006] In order to achieve the above-mentioned object, the heating cooker of the present disclosure comprises a heating chamber that contains food, a heating unit that heats the food contained in the heating chamber, an irradiation unit that irradiates the heating chamber with irradiation light of a first wavelength that has a relatively high absorbance of water and irradiation light of a second wavelength that has a relatively low absorbance of water, a light receiving unit that receives reflected light of the first wavelength and reflected light of the second wavelength that are reflected by the heating chamber, and a control unit that controls the heating unit based on changes in the amount of light of each of the reflected light of the first wavelength and the reflected light of the second wavelength that are received by the light receiving unit over time.

[0007] According to the present disclosure, food can be heated in a more appropriate manner.

[0008] a schematic diagram illustrating a method for correcting the amount of reflected light using light of a second wavelength; a schematic diagram illustrating a method for irradiating light of the first wavelength and light of the second wavelength in a time-division manner using a multi-chip LED; a plan view illustrating an air blowing means according to the first embodiment and its peripheral configuration; a flowchart illustrating each process when the heat cooker according to the first embodiment executes an example of a heating course; a graph illustrating the results of an experiment in which light of the first wavelength and light of the second wavelength are irradiated to food in a time-division manner and the amount of reflected light of each wavelength is measured in a heat cooker according to the second embodiment; a flowchart illustrating each process when the heat cooker according to the second embodiment executes an example of a heating course;

[0009] According to a first aspect of the present disclosure, there is provided a heating cooker comprising: a heating chamber for accommodating food; a heating unit for heating the food accommodated in the heating chamber; an irradiation unit for irradiating the heating chamber with irradiation light of a first wavelength at which the absorbance of water is relatively high and irradiation light of a second wavelength at which the absorbance of water is relatively low; a light receiving unit for receiving reflected light of the first wavelength and reflected light of the second wavelength reflected by the heating chamber; and a control unit for controlling the heating unit based on changes in the amount of light of each of the reflected light of the first wavelength and the reflected light of the second wavelength received by the light receiving unit over time.

[0010] According to a second aspect of the present disclosure, there is provided the cooking device according to the first aspect, wherein the irradiating unit irradiates the irradiation light of the first wavelength and the irradiation light of the second wavelength in a time-division manner.

[0011] According to a third aspect of the present disclosure, there is provided a heating cooker as described in the first or second aspect, wherein the irradiation unit is equipped with a multi-chip LED having a first LED chip that irradiates irradiation light of the first wavelength and a second LED chip that irradiates irradiation light of the second wavelength.

[0012] According to a fourth aspect of the present disclosure, there is provided the cooking device according to any one of the first to third aspects, wherein the first wavelength is within a range of 970 nm to 990 nm.

[0013] According to a fifth aspect of the present disclosure, there is provided the cooking device according to any one of the first to fourth aspects, wherein the second wavelength is within a range of 380 nm to 940 nm.

[0014] According to a sixth aspect of the present disclosure, there is provided a heating cooker described in any one of the first to fifth aspects, wherein the control unit determines the characteristics of the food based on the amount of reflected light of the second wavelength received by the light receiving unit, and changes the control method of the heating unit based on the determination result.

[0015] According to a seventh aspect of the present disclosure, there is provided a heating cooker described in any one of the first to sixth aspects, further comprising a lens provided on a wall surface of the heating chamber, and an optical transmission means connecting the lens to the irradiation unit and the light receiving unit.

[0016] According to an eighth aspect of the present disclosure, there is provided the cooking device according to the seventh aspect, wherein the wall surface is a side surface of the heating chamber.

[0017] According to a ninth aspect of the present disclosure, there is provided a heating cooker as described in the seventh or eighth aspect, further comprising a temperature sensor for measuring the temperature of the heating chamber, the temperature sensor being provided on the wall surface of the heating chamber.

[0018] According to a tenth aspect of the present disclosure, there is provided the cooking device according to the ninth aspect, further comprising a blower arranged to supply air toward both the lens and the temperature sensor.

[0019] Hereinafter, exemplary embodiments of a cooking device according to the present disclosure will be described with reference to the accompanying drawings. The present disclosure is not limited to the specific configurations of the following embodiments, and configurations based on similar technical ideas are included in the present disclosure.

[0020] First Embodiment First, with reference to FIG. 1, a cooking device according to a first embodiment of the present disclosure will be described.

[0021] FIG. 1 is a perspective view schematically illustrating an external appearance of a cooking device 2 according to a first embodiment.

[0022] 1 is a cooking appliance (a so-called "microwave oven") for cooking food F by microwaves. The food F may be any type of food, such as meat.

[0023] As shown in FIG. 1 , the cooking appliance 2 includes a housing 4, a door 6, a handle 8, an operation display unit 10, a heating unit 12, a light source unit 14, an irradiation / receiving lens 16, a temperature sensor 18, and a control unit 20.

[0024] The housing 4 is a member that forms the outer frame of the cooking appliance 2, and has the heating chamber 3 inside. The heating chamber 3 is a space for heating food F, and is opened and closed by a door 6. The door 6 is opened and closed by a user holding a handle 8. Figure 1 illustrates the door 6 in an open state.

[0025] The operation and display unit 10 is a part for allowing the user to operate the cooking appliance 2 and for displaying information to the user. The operation and display unit 10 of the first embodiment includes an operation unit such as buttons and dials that enable the user to operate the cooking appliance 2, and a display unit that displays information such as heating conditions.

[0026] The heating unit 12 is a means for heating the food F contained in the heating chamber 3. The heating unit 12 of the first embodiment includes a magnetron and a waveguide disposed below the heating chamber 3. Microwaves generated by the magnetron of the heating unit 12 are supplied to the heating chamber 3 through the waveguide, thereby microwave-heating the food F. The microwave frequency is, for example, in the range of 300 MHz to 300 GHz. 300 MHz to 300 GHz means 300 MHz or higher and 300 GHz or lower (the same applies to other numerical notations).

[0027] The light source unit 14 is a unit that generates light for detecting changes in the state of the food F caused by heating. The light source unit 14 is connected to the irradiating / receiving lens 16 via an optical fiber 22 that serves as a light transmitting means.

[0028] The irradiation / receiving lens 16 is a lens that has the function of irradiating the light generated by the light source unit 14 toward the food F in the heating chamber 3. The irradiation / receiving lens 16 also has the function of receiving reflected light that is generated when the light irradiated toward the food F is reflected. The irradiation / receiving lens 16 in the first embodiment is a collimating lens provided on the side wall of the heating chamber 3.

[0029] The orientation of the irradiation / light-receiving lens 16 is set to an orientation that irradiates light toward the center of the bottom surface of the heating chamber 3. The position and orientation of the irradiation / light-receiving lens 16 in the first embodiment are fixed. However, this is not limiting and a driving unit that drives the irradiation / light-receiving lens may be provided to make it movable.

[0030] The temperature sensor 18 is a sensor for detecting the temperature of the food F contained in the heating chamber 3. The temperature sensor 18 may be any type of sensor, such as an infrared sensor, as long as it can measure the temperature of the food F directly or indirectly.

[0031] 1, the irradiation / receiving lens 16 and the temperature sensor 18 are provided on the same wall surface 19 of the heating chamber 3. In the first embodiment, the wall surface 19 is a side wall surface of the heating chamber 3. The configuration is not limited to that shown in FIG. 1, and the irradiation / receiving lens and the temperature sensor may be provided on different wall surfaces of the heating chamber 3 (for example, side wall surfaces facing each other).

[0032] Providing the light emitting / receiving lens 16 and the temperature sensor 18 on the same wall surface 19 leads to space saving and miniaturization of the cooking appliance 2. Furthermore, since the wall surface 19 is a side wall surface of the heating chamber 3, the space around the heating chamber 3 can be effectively utilized, for example, by placing a heater in the space above the heating chamber 3 or by providing a steam generator on the opposing side wall surface.

[0033] The control unit 20 is a member that controls each component of the cooking appliance 2, and is configured with, for example, a microcomputer. The control unit 20 includes, for example, a general-purpose processor such as a CPU or MPU that executes programs to realize predetermined functions. The control unit 20 performs various controls of the cooking appliance 2, for example, by calling and executing programs stored in a memory (not shown). The control unit 20 is not limited to a unit that realizes predetermined functions through the cooperation of hardware and software, and may be a hardware circuit designed specifically to realize predetermined functions.

[0034] Next, the configuration of the light source unit 14 and the optical fiber 22 will be described with reference to Fig. 2. Fig. 2 is a schematic diagram showing the light source unit 14 and its peripheral configuration.

[0035] As shown in FIG. 2, the light source unit 14 includes a multi-chip LED 24, a driver circuit 26, a photodiode 28, an amplifier circuit 30, a CPU 32, and a power supply circuit 34.

[0036] The multi-chip LED 24 is an LED package that has the function of emitting light of at least two wavelengths. The multi-chip LED 24 of the first embodiment has a first LED chip 24A and a second LED chip 24B.

[0037] The first LED chip 24A is an LED chip capable of emitting light of a first wavelength. The second LED chip 24B is an LED chip capable of emitting light of a second wavelength different from the first wavelength. The values ​​of the first wavelength and the second wavelength are set in advance based on the absorbance of water ("water absorbance"). Specifically, the values ​​of each wavelength are set so that the water absorbance of the first wavelength is higher than that of the second wavelength.

[0038] FIG. 3 shows a graph (water absorption spectrum) showing the relationship between the wavelength of light and the water absorbance.

[0039] In the graph of FIG. 3, the horizontal axis represents wavelength (unit: nm), and the vertical axis represents water absorbance (unit: log[1 / T]).

[0040] 3 shows an example of a wavelength range of 700 nm to 1100 nm. The wavelength range of 700 nm to 2500 nm belongs to "near infrared light."

[0041] 3, when the wavelength is around 980 nm, the water absorbance is relatively higher than at other wavelengths. In the first embodiment, the first wavelength of the light emitted by the first LED chip 24A is set to be in the range of 970 nm to 990 nm (for example, 980 nm).

[0042] The second wavelength may be a wavelength having a lower water absorbance than the first wavelength. In the first embodiment, the second wavelength is set within the range of 380 nm to 940 nm (for example, 617 nm).

[0043] The multi-chip LED 24 having the above configuration has the function of selectively (e.g., in a time-division manner) irradiating light of a first wavelength from the first LED chip 24A and light of a second wavelength from the second LED chip 24B. Use of the multi-chip LED 24 makes it possible to selectively irradiate light of two wavelengths without using a mirror, optical filter, sector, etc., which leads to the miniaturization of the light source unit 14 and the cooking appliance 2.

[0044] The driver circuit 26 is a circuit for driving the multi-chip LED 24. The driver circuit 26 of the first embodiment can drive the multi-chip LED 24 so as to generate light of a first wavelength from the first LED chip 24A and light of a second wavelength from the second LED chip 24B in a time-division manner.

[0045] The photodiode 28 is a component capable of converting into a voltage the amount of light (reflected light) received via the light-irradiating / receiving lens 16. The photodiode 28 of the first embodiment has different sensitivities for different wavelengths of light received.

[0046] The amplifier circuit 30 is a circuit for amplifying the voltage output by the photodiode 28 .

[0047] The CPU 32 is a device for controlling each component of the light source unit 14. The CPU 32 is connected to at least the driver circuit 26, the amplifier circuit 30, and the power supply circuit .

[0048] The power supply circuit 34 is a circuit that functions as a power supply for the light source unit 14 .

[0049] The light source unit 14 having the above configuration is electrically connected to the control unit 20 of the cooking appliance 2 and causes the multi-chip LED 24 to emit light of two wavelengths in a time-division manner based on commands from the control unit 20. The emitted light is irradiated toward the food F in the heating chamber 3 via the optical fiber 22 and the irradiation / reception lens 16. The irradiated light (irradiation light) is reflected by the food F, generating reflected light in the heating chamber 3, which is received by the irradiation / reception lens 16 provided on the wall surface 19 of the heating chamber 3. The reflected light received by the irradiation / reception lens 16 is transmitted via the optical fiber 22 to the photodiode 28 and converted into a voltage value, which is then amplified by the amplifier circuit 30.

[0050] The light source unit 14 transmits the voltage value output from the amplifier circuit 30 to the control unit 20. Based on the received voltage value, the control unit 20 obtains information about the amount of reflected light corresponding to the voltage value.

[0051] 2, the light source unit 14 has connection portions 36A and 36B for connecting the optical fiber 22 to the light source unit 14. The first connection portion 36A connects the first optical fiber 22A of the optical fiber 22 to the multi-chip LED 24, and the second connection portion 36B connects the second optical fiber 22B of the optical fiber 22 to the photodiode 28.

[0052] The first optical fiber 22A is connected to the multi-chip LED 24 via a first connection portion 36A, and transmits light generated by the multi-chip LED 24 to the illumination / reception lens 16. The second optical fiber 22B is connected to the photodiode 28 via a second connection portion 36B, and transmits reflected light received by the illumination / reception lens 16 to the photodiode 28.

[0053] In the above configuration, light of a first wavelength, which has a relatively high water absorbance, is irradiated toward the heating chamber 3, and the control unit 20 acquires information regarding the amount of reflected light, thereby making it possible to perform heating control of the food F while indirectly detecting changes in the state of the food F (particularly changes in the moisture content) that occur during heating.

[0054] FIG. 4 is a cross-sectional view that schematically shows the behavior of the first wavelength irradiation light 38 that is irradiated onto the food F from the light source unit 14.

[0055] When the first wavelength irradiation light 38 is irradiated onto the food F, the light is divided into absorbed light 40 that is absorbed by the food F, transmitted light 42 that passes through the food F, and reflected light 44 that is reflected by the food F. The proportions of the light amounts are, for example, absorbed light 40, reflected light 44, and transmitted light 42, in descending order.

[0056] Because the light of the first wavelength has a relatively high water absorbance, the proportion of absorbed light 40 is likely to change depending on the amount of water W contained in the food F. The more water W contained in the food F, the greater the proportion of absorbed light 40, and the less water W contained in the food F, the less the proportion of absorbed light 40.

[0057] The moisture W contained in the food F disperses to the outside of the food F as the temperature rises due to heating. As heating progresses, the moisture W contained in the food F decreases, and as the proportion of absorbed light 40 decreases, the proportion of reflected light 44 increases relatively. Thus, by detecting an increase in the amount of reflected light 44, it is possible to indirectly detect a change in the state of the food F due to heating (≒ a decrease in moisture content).

[0058] The moisture W scattered outside the food F diffuses into the heating chamber 3. The moisture W diffused into the heating chamber 3 also absorbs a portion of the irradiated light 38, but this amount is small compared to the amount of moisture W contained in the food F, and the effect of light absorption by the diffused moisture W can be substantially ignored.

[0059] The cooking appliance 2 of the first embodiment receives reflected light 44 of the first wavelength using the light-emitting / light-receiving lens 16, acquires information (voltage value) related to the light intensity of the reflected light 44 using the photodiode 28 and the amplifier circuit 30, and uses the acquired information to control the heating of the cooking appliance 2. For example, when the voltage value output from the light source unit 14 exceeds a predetermined threshold after the start of a heating course, the control unit 20 determines that the heating of the food F has progressed to the desired state, and stops the heating unit 12 or changes the heating method used by the heating unit 12.

[0060] The cooking device 2 of the first embodiment further irradiates the heating chamber 3 with light of a second wavelength, which has a relatively low water absorbance, and the control unit 20 acquires information about the amount of reflected light, thereby correcting the information about the amount of reflected light of the first wavelength, which is easily affected by the moisture content, with information about the amount of reflected light of the second wavelength, which is less affected by the moisture content. This makes it possible to more accurately estimate changes in the state of the food F as it is heated, while controlling the heating of the food F.

[0061] 5 is a schematic graph illustrating a method for correcting the light amount using light of the second wavelength, in which the horizontal axis represents time (unit: seconds) and the vertical axis represents the amount of reflected light 44 (amount of reflected light / voltage value (unit: V)).

[0062] 5, as heating of food F progresses from time 0 seconds, the amount of reflected light of the first wavelength, which has a relatively high water absorbance, increases as the water content of food F decreases. The second wavelength, which has a relatively low water absorbance, is less affected by changes in the water content of food F, and therefore the increase in the amount of reflected light is small (for example, there is almost no change).

[0063] When the food F is heated to a certain extent, the food F may be significantly deformed (e.g., warped). When the food F is deformed, the direction of the reflected light 44 reflected by the food F changes, and the amount of reflected light 44 received by the light-emitting / receiving lens 16 changes. In the example shown in Figure 5, the amount of reflected light increases, but the amount of reflected light may also decrease (e.g., in the early stages of heating).

[0064] The control unit 20 corrects the amount of reflected light at the first wavelength in response to significant changes in the amount of reflected light at the second wavelength. As shown in FIG. 5 , the amount of reflected light at the first wavelength increases as the moisture content of the food F decreases during heating, whereas the amount of reflected light at the second wavelength remains unchanged, independent of changes in moisture content. However, when food F is deformed, the amount of reflected light at both the first and second wavelengths changes, as shown in FIG. 5 . By adjusting the light output at the first wavelength from the first LED chip 24A and the light output at the second wavelength from the second LED chip 24B, the amount of change in the amount of reflected light at the first and second wavelengths due to deformation of the food F is the same. Therefore, by calculating the difference in the amount of reflected light at the second wavelength before and after deformation of the food F and subtracting this difference from the amount of reflected light at the first wavelength, the effect of deformation of the food F on the amount of reflected light at the first wavelength can be offset, as shown by the dashed dotted line in FIG. 5 . Using the corrected amount of reflected light information allows for more accurate heating control, which is less susceptible to changes in the shape of the food F. The correction is not limited to using the difference, but the influence of the deformation of the food material may be corrected by using the ratio between the amount of reflected light of the first wavelength and the amount of reflected light of the second wavelength.

[0065] 6 is a schematic diagram for explaining a method of irradiating light of a first wavelength and light of a second wavelength in a time-division manner using a multi-chip LED 24. In FIG. 6, the horizontal axis represents time, and the vertical axis represents the amount of light.

[0066] 6, the first wavelength irradiation light 38 and the second wavelength irradiation light 38 are alternately generated by pulses at a constant frequency. This allows light of two different wavelengths to be generated in a time-division manner. When the first wavelength irradiation light 38 and the second wavelength irradiation light 38 are generated with the same light intensity, the output value (initial value) of the reflected light 44 is approximately constant.

[0067] When food F is heated and a change in state occurs, a difference occurs between the amount of reflected light at the first wavelength and the amount of reflected light at the second wavelength, as shown in the bottom graph of Figure 6. This difference indicates the actual amount of change in moisture content of food F.

[0068] 1, a blower (not shown) for supplying an air curtain is provided on the wall surface 19. The blower will be described with reference to FIG.

[0069] FIG. 7 is a plan view schematically showing the blower 46 and its surrounding structure.

[0070] 7, in the internal space of the wall surface 19 (the external space of the heating chamber 3), in addition to the irradiation / receiving lens 16 and the temperature sensor 18, a blower 46 is provided. The blower 46 may be any blower having a blowing function, such as an electric fan.

[0071] The air blowing unit 46 is disposed so as to blow air toward both the irradiation / light-receiving lens 16 and the temperature sensor 18. In the example shown in Fig. 7, the air blowing unit 46 blows air toward the area in front of the irradiation / light-receiving lens 16, and the air that passes through this area passes through the area in front of the temperature sensor 18. In this way, air is blown toward both the irradiation / light-receiving lens 16 and the temperature sensor 18. In the example shown in Fig. 7, the air blowing unit 46 blows air sideways, but this is not limiting, and the air blowing direction of the air blowing unit 46 may be any direction (for example, upward or downward).

[0072] 7, an air curtain can be supplied to both the irradiation / receiving lens 16 and the temperature sensor 18, suppressing the adhesion of impurities and reducing measurement errors associated with temperature increases in the heating chamber 3. Sharing one air blower 46 for both the irradiation / receiving lens 16 and the temperature sensor 18 leads to space savings and cost reductions.

[0073] The cooking device 2 having the above configuration executes a predetermined heating course selected by the user on the operation display unit 10 according to the type of food F, etc.

[0074] FIG. 8 is a flowchart showing each process when the cooking device 2 of the first embodiment executes a heating course.

[0075] As shown in Fig. 8, the control unit 20 accepts the start of a heating course (S11). Specifically, the start of the heating course is accepted in response to the user selecting a heating course and pressing the OK button on the operation display unit 10 shown in Fig. 1.

[0076] The control unit 20 executes the heating step (S12). Specifically, the control unit 20 drives the heating unit 12 to execute the heating step corresponding to the heating course selected in step S11. The magnetron of the heating unit 12 is driven to generate microwaves, which are supplied to the heating chamber 3 via a waveguide. The food F is microwave-heated by the microwaves supplied to the heating chamber 3. Note that, in addition to the magnetron, heating may also be performed using an upper heater provided on the upper surface of the heating chamber 3, or, in the case of an oven, a rear heater provided on the rear surface.

[0077] During the heating process, the control unit 20 drives the multi-chip LED 24 of the light source unit 14 together with the heating unit 12. Specifically, the control unit 20 drives the multi-chip LED 24 via the driver circuit 26 so that the first LED chip 24A generates light of a first wavelength and the second LED chip 24B generates light of a second wavelength in a time-division manner. The light of each wavelength (irradiation light 38) generated by the multi-chip LED 24 is irradiated onto the food F contained in the heating chamber 3 via the irradiation / reception lens 16. The irradiation light 38 of each wavelength is reflected by the food F, generating reflected light 44, which is received by the irradiation / reception lens 16. The reflected light 44 of each wavelength received by the irradiation / reception lens 16 is transmitted to the photodiode 28 via the optical fiber 22 and converted into a voltage value. The converted voltage value is amplified for each wavelength by the amplifier circuit 30, and the amplified voltage value is output to the control unit 20. The control unit 20 acquires the output amplified voltage value as information regarding the amount of reflected light of each wavelength.

[0078] The control unit 20 determines whether to terminate the heating process (S13). The control unit 20 in the first embodiment determines whether to terminate the heating process based on the information regarding the reflected light amount of the first wavelength and the information regarding the reflected light amount of the second wavelength acquired in step S12. More specifically, the control unit 20 corrects the reflected light amount of the first wavelength with the reflected light amount of the second wavelength using the method described with reference to FIG. 5, and determines to terminate the heating process when the corrected reflected light amount of the first wavelength exceeds a predetermined threshold (YES in S13).

[0079] As described above, the progress of heating of food F can be accurately determined from information on the amount of reflected light of the first wavelength after correction, and by determining whether or not to terminate the heating process based on this information, food F can be heated in a more appropriate manner depending on changes in the state of food F.

[0080] In particular, by correcting the amount of reflected light of the first wavelength with the amount of reflected light of the second wavelength, even if a local change in the state of the food F (e.g., deformation of the food F) occurs, it is possible to determine the end of the heating process using information that more accurately reflects the state of the food F. This allows the food F to be heated in a more appropriate manner depending on the change in the state of the food F.

[0081] More specifically, by correcting for the effects of deformation of food F, it becomes possible to monitor only the change in moisture content of food F. Food F is mainly composed of moisture, fat, and protein, and for example, when the sensing object is "meat," the moisture content is the highest and the change due to heating is also large, so the change in moisture content and the internal temperature are roughly proportional, and by monitoring the change in moisture content, the internal temperature of food F can be monitored correlatively.

[0082] In steps S12 and S13, the specific control method may be determined not only by the information on the amount of reflected light but also by taking other information (for example, the measurement value of the temperature sensor 18) into consideration.

[0083] When the control unit 20 determines not to end the heating process (NO in S13), it executes step S13 again.

[0084] When the control unit 20 determines that the heating process is to be ended (YES in S13), it notifies the user that cooking is finished (S14). Specifically, it stops driving the heating unit 12 and the light source unit 14, and notifies the user that cooking is finished by means of audio, display, or the like.

[0085] 2, the cooking appliance 2 having the above configuration uses the multi-chip LED 24 to irradiate light of two wavelengths in a time-division manner and the photodiode 28 to receive the reflected light of the two wavelengths, and therefore can be made compact without using a mirror, optical filter, etc. In particular, cooking appliances for home and commercial use such as microwave ovens have size restrictions, and by employing the light source unit 14 and cooking appliance 2 as in embodiment 1 to achieve size restrictions, it becomes easier to commercialize the appliance while complying with the size restrictions.

[0086] (Actions and Effects) As described above, the heating cooker 2 of embodiment 1 comprises a heating chamber 3 that accommodates food F, a heating unit 12 for heating the food F accommodated in the heating chamber 3, a multi-chip LED 24 (irradiation unit) that irradiates, toward the heating chamber 3, irradiation light 38 of a first wavelength at which the absorbance of water is relatively high and irradiation light 38 of a second wavelength at which the absorbance of water is relatively low, respectively, a photodiode 28 (light receiving unit) that receives reflected light 44 of the first wavelength and reflected light 44 of the second wavelength reflected by the heating chamber 3, and a control unit 20 that controls the heating unit 12 based on changes in the amount of light of each of the reflected light 44 of the first wavelength and the reflected light 44 of the second wavelength received by the photodiode 28 over time.

[0087] With this configuration, by controlling the heating unit 12 based on the change in the light intensity of each of the reflected light 44 of the first wavelength and the second wavelength over time, the food F can be heated in a more appropriate manner depending on the change in the state of the food F. Note that, although the first embodiment exemplifies the multi-chip LED 24 as the irradiating unit and the photodiode 28 as the light receiving unit, this is not limiting. Any component may be used as the irradiating unit as long as it has the function of irradiating the first wavelength and the second wavelength toward the heating chamber 12. Any component may be used as the light receiving unit as long as it has the function of receiving the first wavelength and the second wavelength reflected by the heating chamber 12.

[0088] In the cooking appliance 2 of the first embodiment, the multi-chip LED 24 (irradiation unit) irradiates the first wavelength irradiation light 38 and the second wavelength irradiation light 38 in a time-division manner. With this configuration, it is possible to irradiate light of two different wavelengths using one multi-chip LED 24, which leads to a reduction in the size of the cooking appliance 2.

[0089] In the cooking appliance 2 of the first embodiment, the multi-chip LED 24 (irradiation unit) has a first LED chip 24A that irradiates irradiation light 38 of the first wavelength and a second LED chip 24B that irradiates irradiation light 38 of the second wavelength. With this configuration, it is possible to irradiate light of two different wavelengths using one multi-chip LED 24, which leads to a reduction in the size of the cooking appliance 2.

[0090] Furthermore, in the cooking device 2 of the first embodiment, the first wavelength is in the range of 970 nm to 990 nm. With this configuration, a wavelength at which water has a high absorbance can be used as the first wavelength. This makes it possible to monitor the amount of moisture change inside the food F. Note that the first wavelength is not limited to the range of 970 nm to 990 nm, and other wavelength ranges may be used as long as they have a higher water absorbance than the second wavelength (for example, a range including 750 nm, a range including 1540 nm, a range including 1940 nm, or a range including 2900 nm).

[0091] In the cooking device 2 of the first embodiment, the second wavelength is in the range of 380 nm to 940 nm. With this configuration, a wavelength at which water absorbs light less can be used as the second wavelength. Note that the second wavelength is not limited to the range of 380 nm to 940 nm, and other wavelength ranges may be used as long as the wavelength has a lower water absorbance than the first wavelength.

[0092] The cooking appliance 2 of the first embodiment further includes an irradiation / receiving lens 16 (lens) provided on a wall surface 19 of the heating chamber 3, and an optical fiber 22 (light transmitting means) connecting the irradiation / receiving lens 16 to the multi-chip LED 24 (irradiation unit) and the photodiode 28 (light receiving unit). With this configuration, light irradiation and light reception can be performed with a simple configuration.

[0093] In the cooking device 2 of the first embodiment, the wall surface 19 is a side surface of the heating chamber 3. With this configuration, the space around the heating chamber 3 can be effectively utilized.

[0094] Cooking appliance 2 of embodiment 1 further includes air blowing means 46 that is provided to supply air toward both irradiation / reception lens 16 (lens) and temperature sensor 18. With this configuration, the air curtain supplied by air blowing means 46 can be shared by irradiation / reception lens 16 and temperature sensor 18, leading to a reduction in size and cost of cooking appliance 2.

[0095] (Embodiment 2) A cooking device 2 according to embodiment 2 will be described with reference to Figures 9 and 10. Descriptions that overlap with embodiment 1 will be omitted where appropriate.

[0096] 9 is a graph showing the results of an experiment in which light of the first wavelength and light of the second wavelength were irradiated onto food F in a time-division manner and the amount of reflected light at each wavelength was measured. In Fig. 9, the horizontal axis represents the amount of reflected light at the first wavelength / voltage value (unit: V), and the vertical axis represents the amount of reflected light at the second wavelength / voltage value (unit: V).

[0097] 9, three types of food F were used: "lean beef," "pork," and "chicken." The first wavelength was 980 nm, and the second wavelength was 617 nm.

[0098] As shown in Fig. 9, the amount of reflected light at each wavelength tended to differ depending on the type of food F. When food F was lean beef, the amount of reflected light at the first wavelength and the second wavelength was the smallest, when food F was chicken, the amount of reflected light at the first wavelength and the second wavelength was the largest, and when food F was pork, the amount of reflected light at the first wavelength and the second wavelength was intermediate.

[0099] Thus, by setting thresholds and boundary values ​​in advance for the absolute values ​​of the reflected light amounts of the first wavelength and the second wavelength, it is possible to accurately determine the type of food F (for example, the type of meat).

[0100] When comparing the amount of reflected light at the first wavelength and the amount of reflected light at the second wavelength, the difference between the types of food F is more pronounced for the amount of reflected light at the second wavelength than for the first wavelength, so the type of food F may be determined based only on the value of the amount of reflected light at the second wavelength.

[0101] FIG. 10 is a flowchart showing each process when the heating course executed by the cooking appliance 2 includes a step of determining the type of food F.

[0102] As shown in FIG. 10, the control unit 20 receives a request to start a heating course (S11), similarly to the flowchart shown in FIG.

[0103] The control unit 20 further determines the type of food F (S21). Specifically, the light source unit 14 is driven to irradiate the food F with light of the first wavelength and the second wavelength in a time-division manner, and the amount of reflected light is measured. Based on the measurement results of the amount of reflected light, the type of food F is determined by utilizing the differences in the tendency of the amount of reflected light for each type of food F shown in Figure 9. More specifically, thresholds and boundary values ​​are set in advance for the values ​​of the amount of reflected light of the first wavelength and the second wavelength, and the type of food F is determined based on the values ​​of the amount of reflected light of the first wavelength and the second wavelength output from the light source unit 14.

[0104] In step S21, the heating unit 12 is stopped and not operated. This allows the type of food F to be accurately determined without being affected by heating by the heating unit 12. Note that the type of food F may not necessarily be determined before the heating step (S22) is performed, but may also be determined during the heating step (S22) while the heating unit 12 is operating.

[0105] The control unit 20 executes the heating step (S22). Specifically, similar to step S12 in the flowchart shown in Fig. 8, the heating unit 12 is driven to heat the food F, while the light source unit 14 is driven to continuously monitor information on the amount of reflected light of the first wavelength and the second wavelength.

[0106] The control unit 20 determines whether or not to terminate the heating process (S23). Specifically, similar to step S13 in the flowchart shown in Fig. 8, the control unit 20 determines whether or not to terminate the heating process based on the value obtained by correcting the amount of reflected light of the first wavelength with the amount of reflected light of the second wavelength.

[0107] In steps S22 and S23, the control method for the heating unit 12 is changed according to the information on the type of food F determined in step S21. For example, in step S22, the output value (wattage) of the magnetron of the heating unit 12 may be changed according to the type of food F, and in step S23, the threshold value for the output value (correction value) of the reflected light amount used to determine whether to end the heating process may be changed according to the type of food F.

[0108] When it is determined that the heating process is to be ended (YES in S23), the control unit 20 notifies the user that cooking has ended (S14).

[0109] As described above, the type of food F is determined from information on the amount of reflected light at the first wavelength and the amount of reflected light at the second wavelength (S21), and the heating conditions in the heating process (S22, S23) are changed based on this information, thereby making it possible to heat the food F in a more appropriate manner.

[0110] As described above, in the heating cooker 2 of embodiment 2, the control unit 20 determines the type (characteristics) of the food F based on the amount of reflected light 44 of the first wavelength and the second wavelength received by the photodiode 28 (light receiving unit), and changes the control method of the heating unit 12 based on the determination result.

[0111] With this configuration, when the amount of reflected light 44 changes depending on the characteristics (type) of food F, the characteristics of food F can be determined based on the amount of reflected light 44, and the control method of heating unit 12 can be changed based on the determination result, thereby heating food F in a more appropriate manner depending on the characteristics of food F.

[0112] (Embodiment 3) A cooking device 2 according to embodiment 3 will be described with reference to Figures 11 and 12. Descriptions that overlap with embodiments 1 and 2 will be omitted as appropriate.

[0113] Fig. 11 is a graph showing the results of an experiment in which light of the second wavelength was irradiated onto food F and the amount of reflected light was measured. In Fig. 11, the horizontal axis represents time (unit: seconds) and the vertical axis represents the amount of reflected light of the second wavelength / voltage value (unit: V).

[0114] In the experimental example of Fig. 11, the same "lean beef" was used as food F, and three different thicknesses of the lean beef, "1.1 cm," "1.7 cm," and "2.5 cm," were used. 617 nm was used as the second wavelength.

[0115] 11, the amount of reflected light at the second wavelength changes depending on the thickness of the food F. In particular, the amount of reflected light differs significantly depending on the thickness of the food F after approximately 3 to 6 seconds have passed since the start of measurement.

[0116] Therefore, by presetting a threshold value or boundary value for the amount of reflected light of the second wavelength after a predetermined time has elapsed after heating has started, it is possible to accurately determine the thickness of the food F.

[0117] FIG. 12 is a flowchart showing each process in a case where the heating course executed by the cooking appliance 2 includes a step of determining the thickness of the food F.

[0118] As shown in Figure 12, the control unit 20 executes a heating process that drives the heating unit 12 and the light source unit 14 (S12), similar to the flowchart shown in Figure 8, and determines the thickness of the food F while executing the heating process (S31).

[0119] Specifically, by utilizing the difference in the tendency of the amount of reflected light for each thickness of food F shown in Figure 11, a threshold / boundary value is set in advance for the amount of reflected light of the second wavelength after a predetermined time has elapsed since the start of heating, and the thickness of food F is determined based on the value of the amount of reflected light of the second wavelength output from light source unit 14.

[0120] In addition, the thickness of the food F may not only be determined during the heating process (S12), but may also be determined by stopping the heating unit 12 before executing the heating process, driving the multi-chip LED 24 to irradiate light of the second wavelength, and measuring the amount of reflected light.

[0121] The control unit 20 determines whether or not to terminate the heating process (S32). Specifically, similar to steps S13 and S23 in the flowcharts shown in Figures 8 and 10, the control unit 20 determines whether or not to terminate the heating process based on the value obtained by correcting the amount of reflected light of the first wavelength with the amount of reflected light of the second wavelength.

[0122] As in the second embodiment, the control method for the heating unit 12 is changed taking into consideration the information on the thickness of the food product F determined in step S31. For example, the output value (wattage) of the magnetron of the heating unit 12 during the heating process may be changed depending on the thickness of the food product F, or a threshold value related to the output value (correction value) of the amount of reflected light used to determine whether to end the heating process in step S32 may be changed.

[0123] As described above, the thickness of the food F is determined from information on the amount of reflected light at the second wavelength (S31), and the heating conditions in the heating process (S12, S32) are changed based on this information, thereby allowing the food F to be heated in a more appropriate manner.

[0124] As described above, in the heating cooker 2 of embodiment 3, the control unit 20 determines the thickness (characteristics) of the food F based on the amount of reflected light 44 of the second wavelength received by the photodiode 28 (light receiving unit), and changes the control method of the heating unit 12 based on the determination result.

[0125] With this configuration, when the amount of reflected light 44 changes depending on the characteristics (thickness) of the food, the characteristics of the food F can be determined based on the amount of reflected light 44, and the control method of the heating unit 12 can be changed based on the determination result, thereby heating the food F in a more appropriate manner depending on the characteristics of the food F.

[0126] The invention of the present disclosure has been described above with reference to the above-mentioned Embodiments 1 to 3, but the invention of the present disclosure is not limited to the above-mentioned Embodiments 1 to 3. For example, in Embodiments 2 and 3, the case where the type and thickness of the food F are identified as characteristics of the food F has been described, but the present disclosure is not limited to such a case. It is also possible to identify characteristics other than the type and thickness of the food F (for example, size or shape change). In this case, the food F may be irradiated with light in a wavelength range in which the output value of the reflected light amount is likely to change depending on the characteristic to be identified.

[0127] Furthermore, in the first to third embodiments, the first and second wavelengths are described as being used. However, this is not limited to this case. A third wavelength different from the first and second wavelengths may also be used. For example, when the second wavelength is 617 nm, the amount of reflected light may vary depending on the color of the food surface. Taking this into consideration, a third wavelength (e.g., 700 nm to 940 nm) in a range that is less affected by differences in food surface color may also be used, and correction may be performed based on information about the amount of reflected light at the third wavelength. Alternatively, instead of using the third wavelength, light in a wavelength range (e.g., 700 nm to 94 nm) that is less affected by differences in food surface color may be used as the second wavelength.

[0128] In addition, in embodiments 1 to 3, the heating cooker 2 is described as being a microwave oven, but this is not limited to such a case and also includes heating cookers that heat in a closed space, and may be any type of heating cooker, such as an oven appliance, a toaster, a stove, or an induction grill.

[0129] Although the present disclosure has been fully described in connection with the preferred embodiments with reference to the accompanying drawings, various variations and modifications will be apparent to those skilled in the art. Such variations and modifications should be understood to be included within the scope of the invention as defined by the appended claims, unless they depart therefrom. Furthermore, changes in the combination and order of elements in each embodiment may be made without departing from the scope and spirit of the present disclosure.

[0130] By appropriately combining any of the above-described embodiments and various modifications, it is possible to achieve the effects of each of the embodiments and modifications.

[0131] The present disclosure is applicable to any cooking device that heats and cooks food such as meat.

[0132] 2 Cooking appliance 3 Heating chamber 4 Housing 6 Door 8 Handle 10 Operation display unit 12 Heating unit 14 Light source unit 16 Irradiation / light receiving lens (lens) 18 Temperature sensor 19 Wall surface 20 Control unit 22 Optical fiber (light transmission means) 24 Multi-chip LED (irradiation unit) 24A First LED chip 24B Second LED chip 26 Driver circuit 28 Photodiode (light receiving unit) 30 Amplifier circuit 32 CPU 34 Power supply circuit 36A First connection unit 36B Second connection unit 38 Irradiation light 40 Absorbed light 42 Transmitted light 44 Reflected light 46 Air blowing means

Claims

1. A cooking device comprising: a heating chamber for accommodating food; a heating unit for heating the food accommodated in the heating chamber; an irradiation unit for irradiating, toward the heating chamber, light of a first wavelength having a relatively high absorbance by water, and light of a second wavelength having a relatively low absorbance by water; a light receiving unit for receiving reflected light of the first wavelength and reflected light of the second wavelength reflected from the heating chamber; and a control unit for controlling the heating unit based on changes over time in the amount of reflected light of the first wavelength and the reflected light of the second wavelength received by the light receiving unit.

2. The cooking device according to claim 1, wherein the irradiation unit irradiates the irradiation light of the first wavelength and the irradiation light of the second wavelength in a time-division manner.

3. The cooking device according to claim 1, wherein the irradiation unit is equipped with a multi-chip LED having a first LED chip that irradiates light of the first wavelength and a second LED chip that irradiates light of the second wavelength.

4. The heating cooker according to claim 1, wherein the first wavelength is within a range of 970 nm to 990 nm.

5. The cooking device according to claim 1, wherein the second wavelength is within a range of 380 nm to 940 nm.

6. The heating cooker according to claim 1, wherein the control unit determines the characteristics of the food based on the amount of reflected light of the second wavelength received by the light receiving unit, and changes the control method of the heating unit based on the determination result.

7. The cooking device according to claim 1, further comprising: a lens provided on a wall surface of the heating chamber; and optical transmission means connecting the lens to the irradiating section and the light receiving section.

8. The cooking device according to claim 7, wherein the wall surface is a side surface of the heating chamber.

9. The cooking device according to claim 7, further comprising a temperature sensor for measuring a temperature of the heating chamber, the temperature sensor being provided on the wall surface of the heating chamber.

10. The cooking device according to claim 9, further comprising a blower means arranged to supply air toward both the lens and the temperature sensor.