WO2020169111A1 - Système de commande pour dispositif de cuisson - Google Patents

Système de commande pour dispositif de cuisson Download PDF

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Publication number
WO2020169111A1
WO2020169111A1 PCT/CN2020/076456 CN2020076456W WO2020169111A1 WO 2020169111 A1 WO2020169111 A1 WO 2020169111A1 CN 2020076456 W CN2020076456 W CN 2020076456W WO 2020169111 A1 WO2020169111 A1 WO 2020169111A1
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WIPO (PCT)
Prior art keywords
food product
light
optical sensor
controller
variable
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PCT/CN2020/076456
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English (en)
Inventor
Luc CHEN
Original Assignee
Chen Luc
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Publication of WO2020169111A1 publication Critical patent/WO2020169111A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/27—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands using photo-electric detection ; circuits for computing concentration
    • G01N21/272—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands using photo-electric detection ; circuits for computing concentration for following a reaction, e.g. for determining photometrically a reaction rate (photometric cinetic analysis)
    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
    • A47J36/00—Parts, details or accessories of cooking-vessels
    • A47J36/32—Time-controlled igniting mechanisms or alarm devices
    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
    • A47J37/00—Baking; Roasting; Grilling; Frying
    • A47J37/06—Roasters; Grills; Sandwich grills
    • A47J37/08—Bread-toasters
    • A47J37/0871—Accessories
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
    • F24C7/00—Stoves or ranges heated by electric energy
    • F24C7/08—Arrangement or mounting of control or safety devices
    • F24C7/082—Arrangement or mounting of control or safety devices on ranges, e.g. control panels, illumination
    • F24C7/085—Arrangement or mounting of control or safety devices on ranges, e.g. control panels, illumination on baking ovens

Definitions

  • the present disclosure relates generally to the field of cooking devices. More specifically, the present disclosure relates to control systems for measuring a level of browning of the food product when being cooked by a cooking device.
  • Cooking devices such as toasters, ovens, bread makers and fryers are used to heat food products to a desired cooked state.
  • a desired cooked state may depend on a particular color, cooking time, internal temperature, and/or external temperature, etc.
  • cooking devices utilize various types of heating elements that are energized in close proximity to the food product. When the food product is exposed to the heating elements for a certain period of time at a certain intensity, then the food product will achieve the desired cooked state. However, if the food product is exposed to the heat generated from the heating elementsfor too short or too long of a period of time, the food product may remain undercooked or become burned. A control system measuring browning of the food canhelp the user to achieve his desiredcooked state.
  • the various embodiments and aspects described herein relate to a control system monitoring the browning level of an exterior surface of the food product while it is being cooked.
  • the browning level of the exterior surface of the food product is measured by an optical sensor.
  • the exterior surface of the food product is exposed to variation in light from other sources such as the heating element itself that can in some embodiments cycle on and off to maintain a constant temperature in the cooking area or sunlight that shines on the food product dependent on shadows and the time of day, the reflection of light off of the exterior surface of the food product is highly variable or too low for the optical sensor and cannot be relied upon.
  • the cooking device described herein may have a supplemental light source which is bright enough to mitigate the perturbation of the variable light sources. The brighter light decreases the variation in sensed light that is not caused by the browning of the food, so that the reflected light off of an exterior surface area of the food product can be a reliable measure of the browning level of the exterior surface are.
  • a control system for a cooking device which includes an optical sensor configured to receive reflected light off of an exterior surface area of the food product and generate a signal relating to a browning of the food product within the cooking chamber; a supplemental light source configured to emit anamount of light toward an exterior surface of the food product tomitigate inaccurate readings of the browning of the food product caused by variations in other variable light sources irradiating onto the food product; and a controller operatively coupled to the optical sensor and configured to monitor, based on the signal on the browning of the food product, a browning level of the food product.
  • a cooking device which includes a housing defining a cooking chamber, a heating element configured to provide thermal energy to heat a food product within the cooking chamber, at least one optical sensor configured to receive reflected light off of an exterior surface area of the food product and generate a signal relating to a browning of the food product within the cooking chamber, a supplemental light source configured to provide a light bright enough so that its optical sensor reading illuminated a food product is at least 1 time greater than the maximum optical sensor reading provided by the heating element illuminated the food product, and a controller operably coupled to at least one optical sensor and configured to determine, based on the signal relating to the browning of the food product, when the food product reaches a desired browning, where the supplemental light source reduces the effect of the heating element on the optical sensor when the controller determines the browning of the food product.
  • a method for determining a level of browning of a surface area of a food product cooked in a cooking device includes the following steps: providing an amount of light onto the measured area of the food product with a supplemental light source to mitigate inaccurate readings of the browning of the food product due to variations in other variable light sources irradiating the food product; receiving, via an optical sensor, light from the measured area and generating a signal on the browning of the food product within the cooking chamber; storing, via a controller, a reference variable L_ref corresponding to a state of the food product before cooking; determining, via the controller, a current variable L corresponding to a browning of the food product during cooking; calculating, via the controller, a ratio of the current variable L to the reference variable L_ref; and determining if the food product has reached the desired browning level according to the ratio, wherein the desired browning level is determined when the ratio is inferior to a threshold.
  • FIG. 1 is a block diagram of a cooking device including a control system, according to an exemplary embodiment
  • FIG. 2 isan experimental graph from tests on spectral sensitivity for a prototype toaster with a light-dependent resistor (LDR) according to an exemplary embodiment
  • FIG. 3 is a voltage divider circuit with an optical sensor according to an exemplary embodiment
  • FIG. 4 is a block diagram of a method of operating a cooking device, according to an exemplary embodiment
  • FIG. 5 is an exploded view of a toaster including a control system, according to an exemplary embodiment
  • FIG. 6 is a horizontal section view of an optical monitoring unit according to various exemplary embodiments.
  • FIG. 7 is an exploded view of an oven including a control system, according to an exemplary embodiment
  • FIG. 8 is an exploded view of an oven including a control system, according to an exemplary embodiment.
  • FIG. 9 is a perspective view of the oven of FIG. 8 according to an exemplary embodiment.
  • Some cooking devices are electronically or mechanically controlled based on a time parameter and/or a temperature parameter.
  • a cooking device may be controlled to heat a volume of air to a target temperature (e.g., 400°F or 204°C) for a predetermined period of time (e.g., 10 minutes) .
  • a target temperature e.g. 400°F or 204°C
  • Such cooking devices may include temperature sensors and timers to facilitate such control. These time and temperature parameters may be adjusted by a user through one or more settings of the cooking device (e.g., through one or more dials or buttons) .
  • a user may determine the correct settings through experimentation, or the user may monitor the cooking process to determine when the desired cooked state is achieved.
  • the user may not know what settings to input and may not always stay nearby the devices to constantly monitor the cooking process, leading to problems such as undercooking or overcooking of food products.
  • a cooking temperature and a cooking time may provoke various chemical reactions within food products, such as Maillard reactions or caramelization. These chemical reactions may transform molecules contained in the cooked food into other molecules having a browned appearance (e.g., exhibiting a relatively low reflectivity) and a desirable flavor and aroma profile (e.g., light and rich aromas) . Accordingly, this browning may be an indicator that the food has reached a desired cooked state. If the food products are heated beyond this point, the food may burn. This can proceed to the point where what remains is mostly carbon residue, having an even lower reflectivity than browned food products.
  • Maillard reactions e.g., exhibiting a relatively low reflectivity
  • a desirable flavor and aroma profile e.g., light and rich aromas
  • control systems for cooking devices described herein utilize this reaction in a feedback loop based on the reflectivity of the food product to produce food products having a desired browning.
  • the term “light” means electromagnetic waves of any frequency. Light can include visible light, ultraviolet light, infrared light, or other types of light. Terms associated with “light” such as “bright” , “luminosity” , “intensity” are also used in abroad meaning including invisible spectrum of light.
  • photodiode also includes phototransistors or photodarlingtons.
  • a cooking device 10 e.g., a toaster, an oven, a bread maker, a fryer, a grill, a microwave oven, a burner, a cooktop, cookware, an industrial cooking machine, etc.
  • the cooking device 10 may have a cooking volume 12 configured to contain one or more food products P.
  • the cooking volume 12 is partially or completely filled with a heat transfer medium or fluid (e.g., air or cooking oil) , shown as heat transfer medium T.
  • a heating element 14 may be configured to provide energy (e.g., thermal energy, microwave energy, etc. ) to heat at least one of the food products P or the heat transfer medium T.
  • the cooking volume 12 may be at least partially surrounded by a layer of an insulative material, shown as thermal insulation 16, that reduces heat transfer from the cooking volume 12 to the surrounding environment.
  • the device 10 may include an actuator.
  • the actuator e.g., a motor, a spring, a lever, a door, a hatch, etc.
  • the food product actuator 18 may be configured to selectively end the cooking process of one or more of the food products P.
  • the food product actuator 18 may remove one or more of the food products P out of the cooking volume 12. For example, a bread toaster may pop the food upward to move the piece of bread away from heating elements 14.
  • the cooking device 10 may include a light generation device (e.g., a light emitting diode (LED) , an incandescent bulb, a fluorescent bulb, etc. ) , shown as light source 20, configured to illuminate the cooking volume 12.
  • This light source 20 may be used by a person to personally view the food product P and the browning progress of the surface of the food product P.
  • the cooking device 10 includes one or more transparent or translucent portions (e.g., windows, apertures, etc. ) , shown as light transmitting portion 22, that permit ambient light from outside sources (e.g., the sun, other lights within a room, etc. ) to enter the cooking volume 12.
  • the light transmitting portion 22 may be a piece of glass or insulate transparent material, through which the person or user may view the condition of the browning process of the food product P, such as a window or an aperture.
  • the device may include a control system 30, which can coexist with other forms of control system such as a timer or a thermostat.
  • the control system 30 for the cooking device 10 may include a controller 32.
  • the controller 32 may include a processor 34 and a memory 36.
  • the controller 32 may be configured to receive information (e.g., data, electrical signals, etc. ) from one or more sensors and control operation of the cooking device 10.
  • the control system 30 may further include a light generation device (e.g., a light emitting diode (LED) , an incandescent bulb, a fluorescent bulb, etc. ) , shown as light source 40.
  • LED light emitting diode
  • the light source 40 may be used to mitigate perturbations of light on the surface of the food product P when measuring reflected light off of a measured area of the food product P with the optical light sensor 46.
  • the light source 40 and/or the light source 20 may be in communication with orcontrolled by the controller 32.
  • the controller controls if the light source 20, 40 is either on or off, or a signal from the light source 20, 40 may be sent to the controller to inform the controller of the state of the light source 20, 40. Based on whether light source 20 and/or 40 is on or off, the controller can determine the increased or decreased amount of lightthat will be measured off of the food product.
  • the light source 40 may be configured to supply light to a light transmission system 42.
  • the light transmission system 42 may transfer the generated light through the thermal insulation 16 and into the cooking volume 12.
  • the light source 40 and the light transmission system may emit the light on a surface area of an exterior surface of the food product P, by way of example and without limitation, the light may be shined over a surface area of about 6.5 cm 2 or 1 square inch.
  • the control system 30 may further include a light sensor, shown as optical sensor 46, in communication with the controller 32.
  • the optical sensor may sense reflected light of a measured area of the exterior surface of the food product where the light from the light source 40 is being shined upon.
  • the optical sensor may sense the light reflectedfrom a smaller surface area compared to the spot where the light from the light source 40 is being shined upon.
  • the optical sensor 46 may sense the light reflected off of about 3.2 cm 2 or 1/2 square inch of the exterior surface of the food product P whereas the light source 40 may shine light over approximately 6.5 cm 2 or 1 square inch area on the exterior surface of the food product P. Moreover, the measured area is within the surface area over which the light source 40 shines light upon.
  • Light from within the cooking volume 12 travels from the cooking volume 12 to the optical sensor 46 through another light transmission system 42.
  • the optical sensor 46 is configured to analyze the light that it receives and provide a corresponding signal to the controller 32.
  • the control system 30 may include a temperature sensor 48 configured to sense a temperature within the cooking volume 12 and provide a corresponding signal to the controller 32.
  • the temperature sensor 48 may sense a temperature of the heat transfer medium T, a food product P, or another temperature.
  • the control system 30 may further include an indicator (e.g., a light, a buzzer, a vibrator, etc. ) , shown as alarm 50, configured to provide an alert to a user.
  • the alarm 50 may be configured to indicate that a food product P is done cooking.
  • the controller 32 may be configured to control the operation of the heating element 14 and/or the food product actuator 18.
  • the control system 30 may further include a user interface 52 through which a user can make one or more selections, or issue one or more commands.
  • the user interface 52 may be operably coupled to the controller 32 or any elements of the cooking device 10.
  • the user interface 52 may include buttons, knobs, dials, switches, levers, touch screens, displays, and/or any other type of user interface device.
  • the user interface 52 may include a user device, such as a laptop or smart phone, in communication with the controller 32 (e.g., over Bluetooth, over WiFi, etc. )
  • each component may communicate with the controller 32 separately.
  • the communications may be otherwise grouped.
  • a user places one or more food products P into the cooking volume 12 and begins a cooking cycle.
  • a user may begin a cooking cycle by pressing a start button or switch operatively coupled to the controller 32.
  • the heating element 14 begins generating thermal energy and light within the cooking volume 12 to cook the food products P.
  • the heating element 14 does not provide any light that might be reflected off of the measured area of the exterior surface of the food product P.
  • the measured area is the area on the exterior surface of the food product where the optical sensor is sensing the reflected light.
  • the heating element turns red, then the red light, or other invisible light such as infrared, may provideadditional light to the measured area.
  • the thermal energy from the heating element 14 may pass directly from the cooking device 10 to the food products P (e.g., as in a grill or stove) or may pass to the food products P through the heat transfer medium T (e.g., through air in an oven, through oil in a fryer, etc. ) .
  • the thermal energy elevates the temperature of the food products P, the visual appearance of the food products P begins to change (e.g., the food products P change color, the reflectivity of the food products P change, etc. ) .
  • the controller 32 controls the light sources 20 and/or 40 to begin generating light that is transferred into the cooking volume 12.
  • At least a portion of the light entering the cooking volume 12 engages the food products P, and a portion is reflected from the food products P, and more particularly, is reflected off of the measured area of the exterior surface of the food product.
  • the reflected light on the measured area may vary based on thechange of reflectivity of the food during cooking. It is also a function of other parameters such as the other light sources 20, 40 and ambient light and whether a person is blocking the ambient light.
  • the optical sensor 46 may be positioned in a manner to receive mainly reflected light from the surface area of the food product upon which light is shined upon by the light sources.
  • the optical sensor 46 transfers a signal to the controller 32 based on the reflected light.
  • the controller 32 analyzes this signal to determine the browning of the food products P.
  • browning of the food products P By way of example and without limitation, if the sensed light is getting lower, then this may signify browning of the food product. If the sensed light is below a threshold level or if the sensed light drops a certain percentage below a reference level such as beginning level or max level during the cooking process, then this could signify that the food product has been cooked to a desired browning.
  • the controller 32 may be configured to end the cooking process.
  • the controller 32 may deactivate the heating element 14.
  • the controller 32 may activate the food product actuator 18 to remove the food products P from the cooking volume 12 (e.g., ejecting toast from a toaster) and/or to expel the heat transfer medium T to the surrounding atmosphere (e.g., opening a door or vent of an oven, etc. ) .
  • the controller 32 may activate the alarm 50 to indicate that the operator should remove the food products P from the cooking device 10 and /or may modify the cooking parameters (e.g. change a temperature, deactivate fans, etc. )
  • the recorded signals depend on the type of optical sensor 46, it can be the voltage of a resistor in a voltage divider circuit with a photodiode, or the resistance of a light-dependent resistor (LDR) , etc...By way of example, in FIG. 2whichisan experimental graph from tests on spectral sensitivity for a prototype toaster with an LDR, where the optical sensor is an LDR targeting an area of a slice of white bread, with no ambient light.
  • FIG. 2 illustrates the graph of the evolution of the resistance of the LDR.
  • the optical sensor signal can influence the optical sensor signal, such as the spectral sensitivity (e.g., the sensitivity to different wavelengths of light) of the optical sensor 46.
  • the spectral sensitivity e.g., the sensitivity to different wavelengths of light
  • an LDR generally containing Cadmium sulphide
  • Other types of optical sensors comprise silicon photodiodes. Photodiodes are generally made with silicon, causing them to have a wider spectral sensitivity range and particularly, more sensitivity to infrared than LDRs.
  • Optical filters e.g., that block part of the infrared spectrum
  • special manufacturing process may change the spectral sensitivity of the photodiodes to make it closer to the spectral sensitivity of the human eye.
  • Such photodiodes may be considered as ambient light sensors (ALS) , and can still be quite sensitive to infrared light.
  • ALS ambient light sensors
  • spectral radiant flux is abbreviated by using the term “flux” .
  • the spectral radiant flux of total light projected on the measured area of the food can vary greatly throughout the cooking process and can influence the optical sensor signal if the optical sensor 46 is sensitive to the wavelengths where the light is variable.
  • An approximate example of a flux study in an oven can be found in the provisional patent application No. 62/809,273 supporting this application, for example, during the cooking process, an increase in flux of the infrared portion of the light occurs, which correlates with the increase of the temperature of the heating elements 14.
  • Wavelengths of visible light generally present the least variation in flux as long as visible light sources are approximately constant.
  • the wavelengths with the greatestdecrease of reflectivity during browning are in the ultraviolet or visible spectrum, at least for a cake.
  • the signals of an LDR can be less susceptible to variable light sources than a silicon photodiode because there are less sensitive to variable infrared, however their use is restricted in Europe under RoHS directives because of their cadmium content.
  • the accuracy of the control system 30 can be determined by its ability to measure the evolution in time of the browning of the food with the signal provided by the optical sensor 46.
  • this signal can be influenced by many parameters other than browning, as seen above, such as variations of light illuminating the measured area, the temperature of the optical sensor 46, the electronic circuit (noise, deviation%) , light received by the optical sensor 46 that is not coming from the measured area, etc...These parameters can be considered as perturbation, reducing the accuracy of the control system 30. The reduction of their influence increases the accuracy of the control system 30.
  • a supplemental light source 40 may provide an amount of light to the surface of the food product P to mitigate inaccurate measures of the browning of the food product.
  • the brighter the supplemental light source 40 is the more it reduces the contribution of other variable light sources in the total flux measured by the optical sensor 46, increasing the accuracy of the control system 30 for measuring the browning.
  • the viewing angle of the supplemental light source 40 i.e., the more collimated the LED is, the less light loss it occurs
  • the performance of the light transmission system also influence the mitigation of the variable light sources.
  • the type of the optical sensor 46 may influence the mitigating effect of the bright supplemental light source 40.
  • photodiodes or ALS may require brighter supplemental light source 40 to mitigate the increase of infrared sensed during the cooking process, compared to LDRs.
  • the minimal brightness for the supplemental light source 40 can be defined by comparing the influence of the supplemental light source 40 to the influence of each variable light source, on the optical sensor signal for a slice of white bread, for example.
  • the influence of the ambient light source on the optical sensor signal can be decreased, for example by a cover on the slots of the toaster or the door of the oven. In this way, the variable light source to mitigate is the heating elements.
  • the supplemental light source 40 may be bright enough so that its optical sensor reading, when illuminating alone a food product, is at least 1 time greater than the maximum optical sensor reading provided by the heating elements illuminating alone the food product, at least for a toaster.
  • the supplemental light source 40 may provide enough light so that its optical sensor reading, when alone, is at least 1 time greater than the maximum optical sensor reading provided by the heating elements and an average ambient light in a kitchen, during daytime, at least for a toaster.
  • Such embodiments do not require the supplemental light source 40 to be pulsed to be differentiated from the other variable light sources.
  • the term “reading of theoptical sensor” is abbreviated by using the term “reading” .
  • the optical sensor 46 is included in a voltage divider circuit.
  • the voltage divider resistor may bein parallel with anAnalog-Digital Converter (ADC) , associatedwith the controller 32.
  • the ADC may provideto the controller 32a reading x of the optical sensor 46 which may be a digital integerwhichdepends on the voltage of the resistor.
  • ADC Analog-Digital Converter
  • the relationship between the reading xand the total radiant flux received by the optical sensor weighted by its spectral sensitivity, designated by the variable L, depends on the type of optical sensor 46, and the electronic circuit.
  • variable L each time the variable L is mentioned or used, it may be replaced by the reading x or any optical sensor reading, and vice versa.
  • the browning level of the measured area is determined by the ratio
  • L_ref can be a value at the beginning of the cooking process, the maximum value, the average value, or any computed value. With the previoushypothesis, the ratio should remain constant during the cooking processuntil decreasing as the food browns, with generally no possible increase.
  • the browning level of the measured area being determined directly by the ratio or more complex function f (x, x_ref) .
  • x_ref is the value of the reading x set asa reference, stored in memory.
  • the ratio may present the advantage of being more accurate for the control system 30 because it is directlyrelated to a quantity of light.
  • the main algorithm implemented in the controller 32 is afeedback loop based on the ratio If the ratio is inferior to a threshold, adjustable by a user setting, the controller can trigger a response, in the form of other algorithm or an action, such as warning the user, or switching off the heating elements.
  • the optical sensor 46 may be one or more of a variety of different optical sensors.
  • the optical sensor 46 may be a photo resistor or light-dependent resistor (LDR) .
  • LDR is a passive component that has an electrical resistance that varies based on the intensity of the light incident on one or more surfaces of the LDR (e.g., the spectral radiant flux) . Specifically, the resistance may decrease when exposed to light of a greater intensity.
  • the use of an LDR may be advantageous due to its capability to respond to a relatively wide range of light intensities.
  • LDRs can be relatively cost effective and reliable.
  • the ratio isdetermined by: in which, R and R_ref are the resistances of the LDR, ⁇ is a technical characteristic of the LDR.
  • the optical sensor 46 may be one or more photodiodes. In embodiments with photodiodes in a circuit as shown in FIG. 3, the ratio is determined by until the photodiodes become saturated due to too much light sensed.
  • LEDs are small components that can fit easily in any toaster.
  • Ovens are often equipped with incandescent lamps that can resist high temperatures (e.g., several hundred degrees Celsius) . Accordingly, incandescent lamps can be used as the light source 20 (e.g., in ovens) . However, there are more sensitive to variations due to heating elements 14 drawinghigh amount ofcurrent on the domesticpower supply linethan a LED with a regulated voltage, so there are influenced by the on-off cycle too. These incandescent lamps are generally used by people to visually inspect the food product as it is being cooked during the cooking process.
  • the light source 20 may electrically communicate or be controlled by the controller..
  • the light source 20 and/or the light source 40 includes mono or polychromatic LEDs, incandescent lamps (e.g., utilizing halogen) , or lasers.
  • Brighter light sources for the light source 40 are desirable light sources to reduce the influence of the heating elements 14 and ambient light on the signal from the optical sensor 46.
  • the variations in light on the exterior surface of the food product can be reduced, together with the effects on the reading (e.g., voltage reading for an LDR) and the impact of the variations in the operation of the cooking device and methods.
  • the amount of ambient light entering the cooking volume 12 may be reduced. Solutions that mitigate ambient light can include structural modification of generic devices in order to cover holes and transparent surfaces through which ambient light could otherwise enter.
  • the optical sensor 46 receives only or primarily light originating from the light source 40, the light source 20, and/or the heating element 14.
  • an optical sensor may be configured to measure the ambient light entering the cooking volume 12, and these measurements may be used by the controller 32 to compensate for the effect of ambient light on the optical sensor signal in the same way that the controller compensates for the effects of the light source 20.
  • the heating elements 14 and/or ambient light are used as light sources.
  • the total amount of flux generated by the heating elements as a function of time is close to a mathematical Hill function.
  • the chance of ambient light modification may be low because of the short operating time of toasters and because their geometries limit the entry of the ambient light.
  • the hardware and data processing components used to implement the various processes, operations, illustrative logics, logical blocks, modules and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose single-or multi-chip processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) , or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein.
  • the processor 34 may be a microprocessor, or, any conventional processor, controller, microcontroller, or state machine.
  • the processor 34 also may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some embodiments, particular processes and methods may be performed by circuitry that is specific to a given function.
  • the memory 36 e.g., memory, memory unit, storage device
  • the memory 36 may be or include volatile memory or non-volatile memory, and may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in the present disclosure. According to an exemplary embodiment, the memory 36 may be communicably connected to the processor 34 via a processing circuit and may include computer code for executing (e.g., by the controller 32 or the processor 34) the one or more processes described herein.
  • the controller 32 includes a microcontroller. In other embodiments (e.g., embodiments where the light within the cooking volume 12 is controlled such that compensation of the signal from the optical sensor 46 is unnecessary) , the controller 32 can include only analog electronic components.
  • the memory 36 may be used to store multiple measures made by the optical sensor 46 throughout cooking operation. For accurate control, computations and mathematical comparisons may utilize this stored data. Optical sensor readings will be analyzed by an algorithm to determine the state of browning of the food and whether cooking should be stopped.
  • the control algorithms of the controller 32 may include various variables, including: (a) an initial measure of light reflected by food (e.g., an uncooked optical sensor reading) , setting a reference for the next measures, (b) a maximal value of the measure, and (c) a percentage between present measured value and maximum, which may be a good indication of the browning level of the food product P. More variables can be added to monitor and/or improve the accuracy of the control scheme and to control progress of cooking.
  • the memory 36 may store one or more values that have recently been measured. During cooking, the optical sensor readings may continuously decrease or increase with a slope that is within a certain range. The magnitude of this slope may be greater than variations caused by other sources, such as the heating elements 14 or slight movement of food due to dehydration. A sudden change of measured values can reveal component malfunction and/or displacement of food.
  • the thermal insulation 16 may be configured to preserve the integrity of the electronic components and to limit the influence of heat on their performance.
  • the arrangement of the thermal insulation 16 may vary between different types of cooking devices 10 based on factors such as thermal constraints, dimensions, and arrangement of components.
  • bread toasters include an opening at their top and operate for one or two minutes at a time. Ovens are enclosed chambers and reach high temperatures for a much longer time. Electronic components of toasters may need less thermal insulation than those of ovens.
  • the optical sensor 46 can be placed at a certain distance from the cooking volume 12 and separated by multiple layers of insulation (e.g., fiberglass, air, etc. ) . Such an arrangement may advantageously not require a fan or any active cooling system. Natural convection of the air around the oven may keep the optical sensor 46 at an acceptable temperature passively.
  • the optical sensor 46 may be covered by part that prevents ambient light from perturbing the measurements of the optical sensor 46.
  • the light guides can be made of any material with high temperature resistance. Metals such as steel or aluminum may be good candidates. Mica or glass may also be used, offering less reflectivity than polished metal and also less thermal conductivity. Light guides may with low thermal conductivities may be desirable, as they may reduce the heat transfer to the electronics.
  • Other solutions to guide light include mirrors, lenses, optical fibers, or transparent pipes. If too much hot air from the heating chamber circulates through the pipes, glass lenses can to be added to block the movement of hot gasses.
  • a protection may be placed in-between them.
  • This protection can be made of any material with high temperature resistance and low thermal conductivity, such as heat resistant plastics.
  • Other alternatives include keeping a small space between the light source 40 and the light guide, and between the optical sensor 46 and the light guide, as air is an excellent insulator.
  • Sleeves made of the same material as the protection may be used to prevent light dispersion around the light source 40 and the optical sensor 46.
  • the controller 32 may receive data from one or more sources.
  • the controller 32 may receive light intensity data from the optical sensors 46, temperature data from the temperature sensors 48, user settings from the user interface 52, and/or other data from other sensors.
  • Each of these components may include an analog-to-digital converter that converts an analog signal (e.g., a current, a resistance, etc. ) to a digital signal that is used by the controller 32.
  • the controller 32 may additionally or alternatively measure the passage of time (e.g., with an internal clock built into the controller 32) .
  • the controller 32 may measure and record the time and/or clock cycle that has elapsed since the beginning of the cooking process (e.g., the point in time where thermal energy is first provided to a food product) .
  • the controller 32 may utilize optical sensor readings from the optical sensor 46.
  • An optical sensor reading may be a resistance, a voltage, a current, a frequency, video data, or another type of sensor reading.
  • the various aspects were discussed in relation to an LDR in which resistance changes as a function of light.
  • the circuit in which the LDR is connected to is designed so that the voltage across the variable portion of the LDR changes as the resistance changes.
  • the optical sensor depending on its type can vary other characteristics and implement the various aspects discussed herein in relation to the characteristic being used to determine light reflection off of the measured area of the exterior surface of the food product.
  • the controller 32 may convert optical sensor readings into a different format (e.g., from a resistance to a digital value proportional to the spectral radiant flux, etc. ) prior to storage and/or to use in calculations.
  • the type of optical sensor 46 used may affect the optical sensor readings.
  • the controller 32 may utilize the data from the optical sensor reading to calculate a variable L, which represents the flux received by the optical sensor 46 (e.g., measured in lumens per square meter for visible light) or any corresponding proportional quantity.
  • the variable L may be weighted by the spectral sensitivity of the optical sensor 46.
  • variable L may only account for flux that can be detected by the optical sensor 46.
  • a lower variable L may correspond to a lesser light intensity (e.g., a lesser radiant flux) being received by the optical sensor 46. Accordingly, in a situation where other sources of light remain constant, a sensor signal level may decrease as the food product P browns.
  • the optical sensor 46 is an LDR. By linearizing the optical sensor reading provided by the optical sensor 46, the calculations are performed using inputs that are proportional to the flux received by the optical sensor 46, which is proportional to the reflectivity of the monitored portion of the food product P. This improves the accuracy of the control system 30.
  • the controller 32 may be configured to compensate (e.g., utilizing one or more algorithms) the optical sensor readings when calculating the variable L.
  • the controller 32 may gradually reduce the variable L associated with a certain optical sensor reading to compensate for the additional radiant flux introduced by the heating elements 14 as the heating elements 14 warm up.
  • the controller may subtract a certain amount of variable L sensed by the optical sensor to account for the increased variable L caused by the heating element when on due to the light the heating element 14 shines on the measured area of the exterior surface of the food product.
  • Various functions may be used to account for other sources of light having outputs that vary over time.
  • the controller 32 may store recent measured variable L data, a maximum variable L, and a minimum variable L for use throughout the method 1000. In some embodiments, the controller 32 calculates and stores an average variable L and/or a mean and/or standard deviation from the maximum variable L for use throughout the method 1000. By way of example, the controller 32 may use such values to monitor or determine the stability of the light sources within the cooking volume 12.
  • a user places one or more food products P into the cooking volume 12.
  • the user selects settings for the cooking process and initiates the cooking process.
  • the user may select the settings using the user interface 52.
  • the settings may include a temperature within the cooking volume 12, a type of food that is being cooked, a desired cooked level (e.g., a “doneness, ” a level of browning, etc. ) , or other parameters. Alternatively, some settings may be automatically detected.
  • the user may initiate the cooking process using the user interface 52.
  • a command to begin the cooking process may be handled by the controller 32, or the command may pass directly to the heating element 14.
  • the temperature sensor 48 may be used in a feedback loop with the heating element 14 to maintain the temperature of the cooking volume 12 at a set point temperature.
  • the controller 32 is configured to determine a temperature of the heat transfer medium T or the food product P based on the signal from the temperature sensor 48.
  • the desired browning level of the food products may be set by the user.
  • a desired browning level of the food products may be associated with a threshold percentage change in the optical sensor reading from the optical sensor 46. This percentage change may be varied based on the type of food product being cooked (e.g., chicken 80%, bread 90%, etc. ) .
  • the controller can stop the heating or cooking action.
  • a user may use the user interface 52 to select a type of food that is being cooked, automatically selecting pre-configured settings such as of browning level, temperature, period of cooking time, change of cooking mode etc.
  • the browning level possible setting may be expressed to the user on the user interface in other ways (e.g., as a color scale) .
  • the controller 32 records a reference value for the variable L (e.g., a maximum or initial variable L) .
  • the controller 32 calculates this variable L using an optical sensor reading from the optical sensor 46 corresponding to the initial state of the food product P. Due to browning, the reflectivity of the food product P will gradually decrease as the food product P cooks. Browning is an irreversible process. Accordingly, the variable L calculated when the food product P is uncooked may represent a maximum variable L. The controller 32 can use the maximum variable L to determine an optical sensor reading that will correspond to the desired browning of the food product P.
  • step 1008 the heating element 14 activates, generating thermal energy and cooking the food product P.
  • the heating element 14 may be activated by the controller 32 or directly by a user. Although step 1008 is shown as occurring after step 1006, in other embodiments, step 1008 occurs at a different point in the process 1000. By way of example, the heating element 14 may already be activated before the food product P is added to the cooking volume 12.
  • the controller 32 monitors optical sensor readings, generating a variable L for each optical sensor reading.
  • the controller 32 may store all of the calculated variable L values in the memory 36. Alternatively, the controller 32 may only store certain variable L values in the memory 36 (e.g., the maximum variable L, the most recently calculated variable L, etc. ) . In some embodiments, the controller 32 also records a time at which each variable L value was measured and/or calculated.
  • the controller 32 may continuously provide optical signal readings (e.g., if the optical sensor 46 is an analog sensor) , or the controller 32 may provide optical signal readings periodically (e.g., once per second, once every 10 seconds, etc. ) .
  • the light from the variable light sources changes while cooking.
  • the heating element turns on and off giving off light when on and not giving off light when off.
  • the person’s shadow might darken the area being measured.
  • the controller 32 determines whether or not the variable L value is abnormal.
  • Abnormal variable L values e.g., variable L values that do not correspond to a known pattern, variable L levels that correspond to a known and undesirable pattern, etc.
  • the controller 32 may record an abnormal condition.
  • the controller 32 may record a perturbation.
  • the controller 32 may be configured to record the variable L value that was measured immediately before the perturbation or abnormal condition was recorded. After a threshold number of perturbations occur (e.g., within a predetermined time period) , the controller 32 may record an abnormal condition.
  • the controller 32 may perform one or more actions in response to recording an abnormal condition.
  • the controller 32 is configured to monitor the rate of change of the variable L.
  • the controller 32 may compare the magnitude of the rate of change of the variable L against a predetermined threshold value. Based on the type of cooking device 10 and the type of heating element 14, the cooking device 10 may have a maximum attainable temperature within the cooking volume 12, which corresponds to a maximum or threshold rate of change of the variable L. If the magnitude of the rate of change of the variable L measured by the optical sensor 56 is above this maximum rate of change, this may indicate a component malfunction or a change in the parameters of the cooking process (e.g., the food product P moving, a change in the light provided by a light source, etc. ) , and the controller 32 may record a perturbation or an abnormal condition.
  • the controller 32 monitors a ratio between the current variable L level and the prior variable L level. If this ratio is not within a predetermined range, then the controller 32 may record a perturbation or an abnormal condition. In embodiments where the variable L level is calculated at regular time intervals (e.g., once per second) , this ratio may be similar to (e.g., proportional to) the rate of change of the variable L.
  • variable L received by the optical sensor 46 may increase during a cooking process.
  • food products P may shift positions or change shape (e.g., bread, soufflés, etc. ) during cooking, thereby changing the amount of light that is reflected from the food products P toward the optical sensor 46.
  • a heating element 14 or a light source 20 may output a spectral radiant flux that increases over time (e.g., as the heating element 14 or the light source 20 warms up) .
  • the controller 32 may be configured to tolerate such increases in variable L.
  • variable L increases or otherwise changes and thereafter remains constant at a new constant value for a threshold period of time, this may indicate that some part of the cooking process has changed, but the food product P has not yet begun browning.
  • the controller 32 may set this new constant value as the maximum variable L.
  • the controller 32 varies the flux provided by the light source 40 and/or the light source 20.
  • the controller 32 may determine the variable L with the light source 40 and/or the light source 20 switched off (i.e., inactive) . If the variable L is not within a predetermined range, then the controller 32 may record a perturbation or an abnormal condition.
  • the controller 32 may determine the variable L with the light source 40 and/or the light source 20 switched on. If the variable L is not within a predetermined range, then the controller 32 may record a perturbation or an abnormal condition. In some embodiments, the controller 32 compares the ratio of the variable L with the light sources turned on to the variable L with the light sources switched off against a threshold (e.g., 100) .
  • a threshold e.g. 100
  • the controller 32 may record a perturbation or an abnormal condition in response to a determination that the ratio is less than the threshold. This process may be completed once or multiple times throughout the cooking process. This process may help to determine if the ambient light entering the cooking volume 12 has changed.
  • the values of the variable L with the light source 20 and/or the light source 40 turned on and off is used to determine what component of the variable L is provided by light sources other than the light source 40 and/or the light source 20 (e.g., provided by ambient light that enters the cooking volume 12) . These components may then be subtracted from the variable L to determine a more accurate variable L value.
  • the controller 32 is configured to monitor an elapsed cooking time indicating the amount of time that the food product P has been cooking.
  • the controller 32 may consider the cooking process to have begun when the heating element 14 is activated.
  • the controller 32 may consider the cooking process to have begun when the temperature sensor 48 detects the heat transfer medium T reaching a threshold temperature.
  • the controller may consider the cooking process to have begun in response to an input from a user (e.g., through the user interface 52) .
  • a threshold period of time e.g., 30 seconds, 5 minutes, etc.
  • the controller may record a perturbation or an abnormal condition.
  • the controller 32 is configured to detect when the variable L decreases below a threshold level. This threshold level may vary based on the maximum variable L. In response to determining that the variable L has fallen below the threshold level, the controller 32 may record a perturbation or an abnormal condition.
  • the controller 32 may compare the variable L to a predetermined function (e.g., a variable L level vs time function, etc. ) .
  • the controller 32 may determine if the variable L follows the predetermined function.
  • the controller 32 may determine that the variable L follows the predetermined function if the variable L falls within certain percentage of the value of the function at the current time.
  • the controller 32 may record a perturbation or an abnormal condition.
  • the controller 32 determines if the food product P has reached the desired browning and turn off the oven when the desired browning is present. In one embodiment, the controller 32 calculates a current decrease in variable L level which is equal to the maximum variable L minus the current variable L. The controller 32 may determine that the food product P has reached the desired browning when the current decrease is greater than a threshold decrease (i.e., difference between the max variable L and the current variable L) . It is also contemplated that the controller 32 may determine that the food product P has reached the desired browning when the current variable L value is at a threshold value. In another embodiment, the controller 32 may calculate a ratio of the current variable L to the maximum variable L which determines when the desired browning has been achieved.
  • a threshold decrease i.e., difference between the max variable L and the current variable L
  • the controller 32 may determine that the food product P has reached the desired browning when the ratio is greater than a threshold ratio.
  • the oven or toaster is then turned off or the food product may be ejected to stop the active heating of the food product by the oven or toaster.
  • These control schemes may be relatively insensitive to long-term changes in optical sensor readings (e.g., due to accumulation of contaminants on the optical sensor 46) , because they are based on a change in variable L, not a specific target variable L. Additionally, these control schemes may be useful where the variable L from the light source 40 is much greater than the variable L from other light sources (e.g., ambient light, the heating element 14, light source 20, etc. ) .
  • the threshold variable L value, variable Ldecrease or ratio may vary based on the type of food that was selected by the user. Alternatively, the user may select the threshold variable L value, variable Ldecrease or ratio with the user interface 52 (e.g., to select a desired brownness) . In another embodiment, the controller 32 compares the sensor signal level to a predetermined function of sensor signal level over time. In some embodiments, the controller 32 determines that the food product P has reached the desired browning when the sensor signal level has reached a predetermined point of the function. For example, if an LDR is used to measure the reflectivity of the measured area on the food product, then the reflectivity is based on a voltage difference. The LDR senses reflectivity and the voltage difference across the circuit changes.
  • the change in voltage is directly proportional to the intensity of the light coming from the measured area of the food product.
  • the controller can turn off the oven or toaster or eject the food product when the desired browning has been achieved.
  • the controller 32 may determine that the food product P has reached the desired browning when the sensor signal level is lower than a predetermined threshold sensor signal level. In response to determining that the food product P has reached the desired browning, the process 1000 may continue to step 1016.
  • the controller 32 performs one or more actions based on a determination that the optical sensor signal is abnormal (e.g., recording an abnormal condition) or a determination that the food product P has reached the desired browning.
  • the action includes ending the cooking process.
  • the controller 32 may deactivate the heating element 14.
  • the controller 32 may end the cooking process by activating the food product actuator 18 and expelling the food product P from the cooking volume 12 (e.g., as in the spring mechanism of a toaster) .
  • the controller 32 may end the cooking process by activating the food product actuator 18 to expel the heat transfer medium from the cooking volume 12 (e.g., venting heated air into the surrounding atmosphere, etc. ) .
  • step 1016 When step 1016 is initiated in response to determining that the food product P has reached the desired browning, this prevents the food product P from reaching an overcooked or burnt state. When step 1016 is initiated in response to determining that the sensor signal level is abnormal, this may prevent damage to the cooking device 10, the food product P, and or the surroundings.
  • the action of step 1016 includes activating the alarm 50 to alert a user.
  • the alarm 50 provides an auditory, visual, tactile (e.g., a vibration) , or other type of indication.
  • the alarm 50 may indicate that the cooking device 10 has malfunctioned, that the food product P has reached the desired browning or will soon reach the desired browning (e.g., in a predetermined period of time) , or other information.
  • the alarm 50 provides different notifications based on what event triggers the alarm (e.g., the food product reaching the desired browning vs. a malfunction being detected) .
  • a user is permitted to set different alarm thresholds or triggers (e.g., the time at which the alarm 50 is triggered) .
  • the action of step 1016 includes entering a functioning or backup mode of operation.
  • the controller 32 may enter the backup mode of operation in response to recording an abnormal condition. While in the backup mode of operation, the controller 32 may determine whether or not the food product P is in the desired browning without the use of the optical sensor 46. Instead, the controller 32 may determine that the food product P has reached the desired browning based the amount of time that the food product P has been cooking. The controller 32 may determine that the food product P has reached the desired browning when the food product P has been cooking for a threshold period of time.
  • the controller 32 is configured to monitor the variable L to determine when the food product P has entered a browning state (i.e., begun browning) .
  • the controller 32 may determine a browning threshold variable L based on the maximum variable L.
  • the browning threshold variable L may be a certain percentage of the maximum variable L.
  • the browning threshold variable L may be the maximum variable L minus a predetermined value.
  • the controller 32 may determine that the food product has entered the browning state when the current variable L is less than the browning threshold variable L. In response to a determination that the food product P has entered the browning state, the controller 32 may perform step 1016.
  • the controller 32 may activate the alarm 50 to alert the user that browning has begun.
  • the controller may change a heating mode of the cooking device 10 (e.g., change a power level of the heating element 14, turn the heating element 14 off, etc. ) .
  • the cooking device utilizes more than one type of light source 40 and/or light source 20 (e.g., two light sources 20, one light source 40 and one light source 20, etc. ) .
  • Each light source may be configured to provide a different spectral radiant flux.
  • each light source may provide flux in a different span of wavelengths (e.g., one provides green light while another provides red light, etc. ) .
  • one light source is used with one type of optical sensor 46, and another light source is used with another type of optical sensor 46.
  • different light sources are used for different purposes.
  • the controller 32 may switch the light source at a certain point in the cooking process (e.g., when the food product P begins browning) .
  • the controller 32 may switch between different light sources based on the type of food that is being cooked.
  • the controller 32 is configured to verify a state of the food product P using another light source and/or another optical sensor 46.
  • the controller 32 may be configured to verify that the food product P has reached the desired browning using another light source and/or another optical sensor 46.
  • the cooking device 10 is a bread toaster 100, according to an exemplary embodiment.
  • the bread toaster includes at least one heating chamber 101, generally made of steel, defining a cooking volume and opened (e.g., along the top of the cooking volume) to insert bread slices or other food products.
  • the heating chamber 101 contains several dividers, shown as mica sheets 102, that contain food products within the heating chamber 101. Mica may be useful for this application, as it can withstand high temperatures and permits the transfer of light therethrough.
  • the heating chamber 101 further contains heating elements, shown as nichrome wires 103, that produce thermal energy in response to receiving an electrical current.
  • the toaster 100 includes other types of heating elements, such as quartz heating elements.
  • the heating chamber 101 has one or more slots or compartments for receiving and toasting slices of bread, shaped by the mica sheets 102. As shown in FIG. 5, the toaster 100 has only one slot. This configuration has the advantage of toasting more evenly one slice of bread only, compared to some embodiments of the toaster 100 having two slots.
  • the nichrome wires 103 for two or more of the slots are directly connected to a power supply (e.g., an AC power supply) , and the supply of electrical energy to the nichrome wires 103 from the power supply may not be controllable other than interrupting the supply (e.g., changing an on/off state) . In such embodiments, heat can build up in the empty slot and pass through the mica sheet 102 between the slots, browning one side of the food product more than the opposite side.
  • the toaster 100 may be activated by pushing down an activator (e.g., a lever, a button, a switch, etc. ) .
  • an activator e.g., a lever, a button, a switch, etc.
  • the toaster 100 may utilize a lever 105 that is accessible from outside the casing 104. As shown, the lever 105 is positioned within a cavity, shown as socket 120, defined by the casing 104.
  • a manipulator e.g., tongs, tweezers, a rod, etc.
  • prehensile tool PT shown as prehensile tool PT
  • the lever 105 may be accessible with or without the prehensile tool PT in the socket 120.
  • the user can use the prehensile tool PT to insert, remove, and carry toast to avoid contacting hot surfaces of the toaster 100 and the toast.
  • the lever 105 When pressed down, the lever 105 closes an electrical circuit of the toaster 100, permitting current to pass through the nichrome wires 103 and begin generating thermal energy.
  • the lever 105 may control the flow of electricity to the nichrome wires 103 directly, or the lever 105 may send a signal to controller 32, and the controller 32 can control the current.
  • a system of spacers, shown as racks 106 may be placed in front of the mica sheets 102 to separate the bread from the nichrome wires 103 and to center the bread between the sets of nichrome wires 103 for even browning.
  • a divider, shown as lateral wall 107, is positioned within the casing 104 substantially parallel with the mica sheets 102.
  • a pair of apertures 108 extend through the mica sheet 102, between the nichrome wires 103, and through the lateral wall 107. As shown, one of the apertures 108 permits light from a light source to enter the heating chamber 101, and the other of the apertures 108 permits reflected light to be received by the optical sensor.
  • the positions of the apertures 108 determine where light encounters, and is reflected from, the bread.
  • the apertures 108 are situated relatively close to the center of the mica sheet 102, as this is generally the hottest location within the toaster 100 and where the bread browns first. In an embodiment with one long slot, if only one optical sensor 46 is used, the apertures 108 may be placed approximately one third of the way down the length of the slot. Because of this positioning, bread is monitored when two pieces of toast are placed into the slot simultaneously.
  • a mark 119 on the top side of the toaster 100 may indicate where the apertures 108 are situated.
  • the apertures 108 should be configured to reduce heat loss from the cooking volume and to reduce signal perturbation caused by the glowing nichrome wires 103.
  • the diameters of the apertures 108 is smaller than the distance between two contiguous lines of nichrome wire 103, and the apertures 108 are arranged such that they do not overlap the nichrome wires 103.
  • the apertures 108 may be large enough and positioned (e.g., near the center of the slot) such that the light source and optical sensor are able to monitor slices of bread having a variety of different widths.
  • the toaster 100 includes an assembly, shown as optical monitoring unit 130 (see Figure 6) , configured to monitor the browning of part of the bread.
  • the optical monitoring unit 130 includes light transmission systems, shown as light pipes 109, that pass through the apertures 108 in the lateral wall 107.
  • the light pipes 109 may have high heat resistance and may be good conductors of light (e.g., mica cylinders or tubes, optical fibers) .
  • One light pipe 109 transmits light from a light source 113 to the bread and another light pipe 109 transmits light reflected by the bread and passing through the aperture 108 to an optical sensor 114.
  • the light source 113 may bea LED whose luminosity is high enough to reduce the effect of other light sources on the determination that the food product P has browned.
  • the light pipes 109 in this example are tubes made of mica, but any optical apparatus like mirrors, lenses, optical fibers, or transparent pipes can be used to direct light to the bread and to the optical sensor 114 and prevent the light from dispersing throughout the interior of the heating chamber 101.
  • the diameters of the apertures 108 in the mica sheet 102 may be smaller than the outer diameters of the light pipes 109 to prevent the light pipes 109 passing through the apertures 108 and into the heating chamber 101.
  • the light pipes 109 are coupled (e.g., fixedly coupled) to a fixture, shown as support 111.
  • This support 111 is coupled (e.g., fastened) to a stable part of the toaster 100 (e.g., the casing 104) .
  • the support 111 may be made from heat resistant material having a low thermal conductivity such that heat from the heating chamber 101 transmitted through the light pipes 109 is insulated and not transmitted to the light source 113 and the optical sensor 114.
  • a round piece of glass 110 with an outer diameter similar to that of the light pipes 109 can be placed at the end of the light pipe 109.
  • the support 111 defines a pair of substantially cylindrical bores, shown as passages 122.
  • the passages 122 are stepped such that they each have two portions with different diameters, one at each end. The first portion is larger and holds the pipes 109 and optionally the glass 110 blocking hot air. The second portion is smaller to prevent the pipes 109 and the glass 110 from exiting the support 111 while still letting light pass therethrough. This geometry prevents direct contact between the pipes 109, the light source 113, and the optical sensor 114.
  • the light source 113 and the optical sensor 114 are coupled (e.g., fixedly coupled) to a circuit board, shown as optical circuit board 115, which is coupled (e.g., fastened) to the support 111.
  • the toaster 100 further includes a second circuit board, shown as main circuit board 124, coupled to the casing 104.
  • the main circuit board 124 includes one or more of: a power supply, an AC/DC converter, an electromagnet, a microcontroller (e.g., the controller 32) , and potentiometers.
  • the main circuit board 124 includes other components.
  • the main circuit board 124 includes a sensor or user interface device, shown as potentiometer 126.
  • the potentiometer 126 includes a knob that is assessable by a user outside of the toaster 100.
  • the potentiometer 126 may be used to select a desired browning of the toast.
  • the main circuit board 124 may be operably coupled to the optical circuit board 115 through one or more cables. In other embodiments, the optical circuit board 115 and the main circuit board 124 are combined into one circuit board.
  • an additional thermal insulator 112 may be added between the support 111 and the electronic board 115.
  • apertures, shown as vents 116, may be defined by the casing 104 to permit hot air to escape to the surrounding atmosphere.
  • one of the light pipes 109 projects the light from the light source along a first axis A1, and the other light pipe 109 returns light to the optical sensor 114 that originates along an axis A2 (e.g., the axes A1 and A2 are centered about the corresponding light pipes 109) .
  • the axes A1 and A2 are angled relative to one another such that they intersect to form a focal point P1 within the heating chamber 101.
  • the axis A1 is oriented at an angle 300 with respect to a line drawn perpendicular to the lateral wall 107, and the axis A2 is oriented at an angle 302 with respect to the same line such that an angle between axis A1 and axis A2 is the sum of 300 and 302.
  • 300 and 302 are substantially equal.
  • 300 and 302 are approximately 13 degrees.
  • the light pipes 109 may be oriented such that the focal point P1 is located along the surface of a piece of bread of average thickness. This arrangement increases the amount of reflected light that is received by the optical sensor 114.
  • the light pipes 109 may be arranged such that axes A1 and A2 are parallel to one another. This arrangement may ease the production of the toaster 100 and thus diminishing its overall cost.
  • the ends of the pipes 109 closest to the mica sheet 102 define a shoulder that permits them to be inserted partially into the apertures 108.
  • the light is cast over a broad area evenly on the surface of the food product P. The sensed area is smaller than the light being cast on the surface of the food product. As such, whether it is a big or small piece of bread or food product in the cooking device, the reflection is measured over a small area of the exterior surface of the food product.
  • multiple optical monitoring units 130 can be incorporated into the cooking device. If so, the plurality of optical monitoring units 130 can take the readings and the readings can be transmitted to the controller and the controller can use the multiple readings of variable L to analyze and determine when the food product has reached the desired browning.
  • the light emitted by the light source 113 is directionally concentrated that the light pipes 109, which would normally concentrate the light emitted by the light source 113, may be omitted.
  • the light pipe 109 associated with the light source 113 may also be omitted in embodiments where the nichrome wires 103 are used a light source.
  • more optical monitoring units 130 can be included to monitor other portions of the bread.
  • control system 30 may be optimized for use with a toaster (e.g., the toaster 100) .
  • An adjustment setting may indicate the percentage of reflected light decrease, or any arbitrary units, to permit the user to choose the state of browning that they prefer.
  • the holes of the toaster e.g., the slots along the top surface
  • the holes of the toaster are covered to limit ambient light coming in. This may be particularly useful for an embodiment where the nichrome wires 103 are used as the light source, with dim red light being emitted from nichrome wires 103.
  • a lever permits attachment of the prehensile tool PT.
  • the activation lever of the toaster 100 can be moved to a position other than the on position or the off position to activate another control function of the toaster 100 (e.g., a stop function) .
  • the light source is a white LED bead with a voltage of about 2.5 Volts, a current of about 0.08 mA, that is to say receiving an electrical power of about 0.2 mW.
  • the luminous efficacity of white LED is about 100 lumens/W.
  • the white LED bead output is about 0.02 lumen, which provides a reading that is about the same as the heating elements at maximum.
  • the optical sensor 114 is an LDR targeting an area of a slice of white bread.
  • the graph of the evolution of the resistance of the LDR is shown in FIG 2, the evolution in time of the light intensity sensed by the LDR is approximately the reversed graph.
  • the toaster is switched on at 5 sec (the lever was maintained in low position to reduce light variation due to the bread movement) .
  • An increase of luminosity in addition with the white LED is expected because the heating elements switched on emit more and more light, however, the resistance of the LDR increases until 33 sec.
  • the increase of luminosity takes place between 33 and 157 sec, after which the browning of the bread decreases the luminosity.
  • Other experiments with brighter LED bead or photodiodes also have shown this effect, of seemingly decreasing luminosity at the beginning of each toasting cycle, during several dozens of seconds.
  • the effect is even more visible when the toaster is empty, with an LDR in FIG. 2.
  • the readings can be delayed for several dozens of seconds after the switch on;
  • An embodiment of the white LED bead with a voltage of about 2.5 Volts, a current of about 0.7 mA, that is to say receiving an electrical power of about 1.75 mW, corresponding to an output of about 0.175 lumen, may be enough to mitigate the effect of ambient light in a daily use.
  • Alternative embodiments can also use UV light source and sensor to have less perturbation from visible and infrared spectrum.
  • the toaster oven 200 defines a heating chamber 201 containing heating elements 202 (e.g., resistive heating elements, natural gas burners, etc. ) .
  • the oven 200 includes a door 203 that is selectively repositionable to permit insertion and removal of food products from the heating chamber 201.
  • the door 203 includes a transparent panel, shown as glass panel 204, situated at the front side of the oven 200 to permit a user to look into the heating chamber 201 without opening the door 203.
  • the door 203 further includes a handle 205 that can be grasped to facilitate opening and closing of the door 203.
  • a light source such as an incandescent lamp 206, facilitates a user observing the browning of the food products.
  • the incandescent lamp 206 may be resistant to the high temperature experienced inside the heating chamber 201 of the oven 200.
  • the oven 200 may include another light source, such as LEDs, positioned outside of the cooking chamber.
  • a light source may be coupled to the handle 205 and oriented to introduce light into the heating chamber 201 through the glass panel 204.
  • User interface devices e.g., knobs, switches, dials, screens, etc.
  • settings controls 207 are placed along the front side of the oven 200 adjacent the door 203. The settings controls 207 may be adjusted by the user to control various aspects of operation of the oven 200 (e.g., the temperature, the cooking time, the type of food being cooked, etc. ) .
  • a dish e.g., a plate, a tray, a bowl, a platter, etc.
  • the plate 208 is configured to facilitate placement of food products in a desired spot within the oven 200.
  • the plate 208 has a marking or designator, shown as sign 209, on a visible surface of the plate 208.
  • sign 209 a marking or designator
  • the sign 209 When a user places a food product into a location indicated by the sign 209 (e.g., directly onto the sign 209) , the food product is located in a spot that permits optimal monitoring of the cooking of the food product.
  • the plate 208 is fixed to the oven 200.
  • the plate 208 is removable from the oven 200 and includes a locating mechanism that facilitates placing the plate 208 in a consistent location (e.g., to facilitate consistently locating the sign 209.
  • the plate 204 may include feet that fit into corresponding cavities defined by the oven 200.
  • the plate 204 may have the same footprint as the heating chamber 201 such that the walls of the heating chamber 201 locate the plate 208.
  • An aperture is defined through the top surface of the heating chamber 201. As shown, the aperture does not directly face any heating element 202.
  • the aperture is covered by a transparent or translucent panel, shown as glass 210, that is coupled to the heating chamber 201.
  • the glass 210 prevents hot air passing through the corresponding aperture.
  • an insulator 212 such as a ceramic fiber blanket, extends around the heating chamber 201 to limit heat transfer out of the heating chamber 201 to the surrounding atmosphere.
  • the insulator 212 may define an aperture aligned with the glass 210.
  • a ring-like element 211 resistant to high temperature, can be added to prevent the insulator 212 from deforming and closing this aperture.
  • the heating chamber 201 and the insulator 212 are at least partially enclosed by a housing, shown as casing 213.
  • a housing shown as casing 213.
  • the apertures through the heating chamber 201, the insulator 212, and the casing 213 may be substantially aligned to permit light to pass therethrough.
  • An optical monitoring unit 230 (e.g., similar to the optical monitoring unit 130) is placed on top of the casing 213 and aligned with the apertures through the heating chamber 201 and the insulator 212.
  • the optical monitoring unit can include a light source and an optical sensor.
  • the optical monitoring unit may be separated from the cooking volume of the heating chamber 201 by one or more layers of air and transparent material.
  • the optical monitoring unit may be isolated from ambient light (e.g., by an opaque tube) .
  • the optical monitoring unit 230 is passively insulated by the glass 214, the insulator 212, and air. Alternatively, the optical monitoring unit 230 can be coupled to the oven without an insulator 212.
  • the optical monitoring unit 230 may comprise at least 2 layers, that can be made of different low conductivity material.
  • the layers may be hollow to retain additional layers of air that have the purpose of thermal insulator.
  • Piece of transparent material can seal the aperture made in the oven to prevent hot air from circulating.
  • the optical sensor is situated at the top layer.
  • the cooking device 10 is a built-in oven.
  • the oven may include one or more heating chambers.
  • a user interface may be placed in a panel above a door to the heating chamber.
  • An optical monitoring unit (e.g., similar to the optical monitoring unit 130) , including optical sensors and light sources may be placed behind a panel of the oven, above and aimed toward a food product.
  • One or more apertures may extend through the top surface of the oven to let light pass through. These apertures may be covered with transparent material to avoid hot air passing through while still letting the light pass through.
  • cooking devices that are used to perform various cooking processes that heat one or more food product.
  • Such cooking devices can include, but are not limited to, toasters, ovens, bread makers, fryers, grills, microwave ovens, burners, cooktops, cookware, and industrial cooking machines.
  • Cooking processes can include, but are not limited to, toasting, broiling, baking, grilling, and frying.
  • Coupled means the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable) . Such joining may be achieved with the two members coupled directly to each other, with the two members coupled to each other using a separate intervening member and any additional intermediate members coupled with one another, or with the two members coupled to each other using an intervening member that is integrally formed as a single unitary body with one of the two members.
  • Coupled or variations thereof are modified by an additional term (e.g., directly coupled)
  • the generic definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means the joining of two members without any separate intervening member) , resulting in a narrower definition than the generic definition of “coupled” provided above.
  • Such coupling may be mechanical, electrical, or fluidic.
  • the present disclosure contemplates methods, systems and program products on any machine-readable media for accomplishing various operations.
  • the embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system.
  • Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon.
  • Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor.
  • machine-readable media can comprise RAM, ROM, EPROM, EEPROM, or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media.
  • Machine-executable instructions include, for example, instructions and data which cause a general-purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

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  • Engineering & Computer Science (AREA)
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  • Physics & Mathematics (AREA)
  • Food Science & Technology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mechanical Engineering (AREA)
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Abstract

La présente invention concerne un système de commande (30) pour un dispositif de cuisson (10) qui peut présenter un capteur optique (46) qui surveille un niveau de brunissement d'une zone de surface extérieure d'un produit alimentaire (T) dans le dispositif de cuisson (10). Le dispositif de cuisson (10) peut présenter une source de lumière supplémentaire (40) qui est suffisamment brillante pour atténuer l'influence de sources de lumière variable éclairant la zone de surface extérieure pour améliorer la précision des mesures du brunissement du produit alimentaire (T).
PCT/CN2020/076456 2019-02-22 2020-02-24 Système de commande pour dispositif de cuisson WO2020169111A1 (fr)

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US201962809273P 2019-02-22 2019-02-22
US62/809,273 2019-02-22

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4245148A (en) * 1979-09-14 1981-01-13 Wisco Industries, Inc. Optically sensitive control circuit for a food browning device
US4363957A (en) * 1979-01-09 1982-12-14 Hitachi Heating Appliances Co., Ltd. Heating apparatus with char detecting and heating controller
US4367388A (en) * 1979-06-06 1983-01-04 Hitachi Heating Appliances Co., Ltd. Cooking heating apparatus
WO1989001279A1 (fr) * 1987-07-29 1989-02-09 Black & Decker Inc. Grille-pain electrique
JPH028622A (ja) * 1988-06-24 1990-01-12 Hitachi Heating Appliance Co Ltd 焦げ目付け加熱調理器
JPH03134410A (ja) * 1989-10-17 1991-06-07 Hitachi Home Tec Ltd 加熱調理装置
CN1360478A (zh) * 1999-07-08 2002-07-24 Seb公司 利用光敏元件响应曲线控制烤面包器内的面包焙烤
CN105765368A (zh) * 2013-09-27 2016-07-13 感应能力有限公司 用于识别食品原料的内容属性的方法和装置

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4363957A (en) * 1979-01-09 1982-12-14 Hitachi Heating Appliances Co., Ltd. Heating apparatus with char detecting and heating controller
US4367388A (en) * 1979-06-06 1983-01-04 Hitachi Heating Appliances Co., Ltd. Cooking heating apparatus
US4245148A (en) * 1979-09-14 1981-01-13 Wisco Industries, Inc. Optically sensitive control circuit for a food browning device
WO1989001279A1 (fr) * 1987-07-29 1989-02-09 Black & Decker Inc. Grille-pain electrique
JPH028622A (ja) * 1988-06-24 1990-01-12 Hitachi Heating Appliance Co Ltd 焦げ目付け加熱調理器
JPH03134410A (ja) * 1989-10-17 1991-06-07 Hitachi Home Tec Ltd 加熱調理装置
CN1360478A (zh) * 1999-07-08 2002-07-24 Seb公司 利用光敏元件响应曲线控制烤面包器内的面包焙烤
CN105765368A (zh) * 2013-09-27 2016-07-13 感应能力有限公司 用于识别食品原料的内容属性的方法和装置

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