Temperature measuring device for a grill, thermometer and grill

Abstract

The present disclosure relates to the technical field of temperature measurement, and provides a temperature measuring device for a grill, a thermometer and a grill. The device comprises a K-type thermocouple element, a pre-processing circuit, an analog-to-digital conversion circuit for converting the pre-processed thermocouple signal into a temperature measuring digital signal, an ambient temperature sensor for collecting a cold end temperature signal of the thermocouple element, and an embedded processor for obtaining a temperature measuring digital sampling value and a cold end signal sampling value from the temperature measuring digital signal and the cold end temperature signal respectively, determining the sign direction of the temperature measuring value according to the temperature measuring digital sampling value, determining a cold end compensation calculation mode according to the sign direction, calculating a compensated temperature measuring signal value from the temperature measuring signal value converted from the sampling value and the cold end temperature signal value according to the cold end compensation calculation mode, converting the compensated temperature measuring value, and obtaining a target temperature measuring value through filtering processing. The K thermocouple with high temperature resistance solves the problem of high temperature damage and failure of the temperature measuring end, and the accurate temperature measuring result is obtained through automatic cold end compensation and filtering.

Description

Technical Field

[0001] This disclosure relates to the field of temperature measurement technology, and more particularly to temperature measuring devices, thermometers, and baking utensils for use in baking. Background Technology

[0002] Currently, temperature measurement in grills such as electric stoves, teppanyaki grills, pizza ovens, and outdoor barbecue grills often uses ambient temperature sensors based on PT1000 platinum resistance thermometers. However, this temperature measurement solution has significant drawbacks in practical use, exhibiting poor practicality and reliability.

[0003] Specifically, when barbecue equipment is in operation, food grease easily drips into the oil collection tray, which can easily ignite and produce an open flame when exposed to high temperatures. Ambient temperature sensors based on PT1000 platinum resistance thermometers are typically mounted on the temperature sensing end. However, the exposed temperature sensing end is easily damaged by the high temperatures of the barbecue flame due to the low temperature resistance (550℃) of the PT1000 platinum resistance thermometer, leading to sensor failure and affecting normal user operation. Furthermore, the high cost of platinum metal results in high production and replacement costs for the sensing end, impacting economic efficiency.

[0004] In summary, existing baking equipment suffers from problems such as the temperature probes being prone to failure under high temperatures and open flames, as well as high costs. Finding a new temperature measurement solution has become a pressing technical problem for the industry. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this disclosure is to provide a temperature measuring device, thermometer and baking oven for baking, which uses a high-temperature resistant thermocouple to solve the problem of high-temperature failure of open flame, and at the same time, cooperates with the back-end signal processing method to ensure the accuracy of temperature measurement, thereby solving the problems in the related technology.

[0006] The first aspect of this disclosure provides a temperature measuring device for baking ovens, comprising: a K-type thermocouple element for acquiring thermocouple signals; a preprocessing circuit electrically connected to the thermocouple element for receiving and preprocessing the thermocouple signals; an analog-to-digital converter circuit connected to the stage following the preprocessing circuit for converting the preprocessed thermocouple signals into temperature-measuring digital signals; wherein the analog-to-digital converter circuit allows data output in two's complement format; an ambient temperature sensor for acquiring ambient temperature signals as cold junction temperature signals of the thermocouple element; and an embedded processor connected to the analog-to-digital converter circuit and the ambient temperature sensor for receiving the temperature-measuring digital signals and the cold junction temperature signals, and obtaining temperature-measuring digital sample values ​​accordingly. The method involves: determining the sign direction of the temperature measurement value corresponding to the digital temperature sample value and / or the disconnection event of the thermocouple element based on a comparison between the digital temperature sample value and at least one range boundary threshold in the range of the analog-to-digital conversion circuit; determining the cold junction compensation calculation method corresponding to the temperature measurement signal value and the cold junction temperature signal value based on the sign direction, wherein the temperature measurement signal value and the cold junction temperature signal value are respectively converted from the digital temperature sample value and the cold junction temperature value; calculating the compensated temperature signal value after the temperature measurement signal value is compensated by the cold junction temperature signal value using the cold junction compensation calculation method; and obtaining the target temperature measurement value by filtering the compensated temperature measurement value converted from the compensated temperature signal value.

[0007] In an embodiment of the first aspect, the filtering process includes: acquiring the current compensated temperature measurement value and historical compensated temperature measurement values, performing smoothing filtering to obtain a smoothed filtered value of the current compensated temperature measurement value; comparing the difference between the current compensated temperature measurement value and the smoothed filtered value to obtain a noise value; determining whether the noise value is greater than a preset threshold; increasing / decreasing an observation noise covariance according to whether the noise value is greater than or less than the preset threshold; wherein the observation noise covariance is used in a Kalman filter; and filtering the current compensated temperature value using the Kalman filter based on the observation noise covariance to obtain the current target temperature measurement value.

[0008] In an embodiment of the first aspect, the preprocessing circuit includes: a thermocouple interface electrically connected to the thermocouple element to receive thermocouple signals and connected to a signal line, the signal line including a positive signal line and a negative signal line; an analog-to-digital conversion circuit connected in the signal line to the stage following the preprocessing circuit, for converting the preprocessed thermocouple signal into a temperature measurement digital signal; the analog-to-digital conversion circuit includes: a differential input interface including a differential positive input terminal connected to the positive signal line and a differential negative input terminal connected to the negative signal line; and an output interface including a temperature measurement digital signal obtained by analog-to-digital conversion based on the differential voltage value between the differential positive input terminal and the differential negative input terminal, so as to obtain a measured temperature signal value based on the temperature measurement digital signal.

[0009] In an embodiment of the first aspect, the preprocessing circuit further includes a disconnection detection circuit, which, in response to detecting that the signal line is disconnected from the thermocouple element, changes the voltage on the differential positive input terminal and / or the differential negative input terminal so that the differential voltage value is at a disconnection voltage value indicating a disconnection.

[0010] In an embodiment of the first aspect, the disconnection detection circuit includes: a first reference voltage unit, including: a resistor voltage divider circuit connected between a first voltage source and ground, wherein the voltage divider point is connected to a first connection point in the positive signal line to set a first reference voltage; and a second reference voltage unit, including: a resistor, one end of which is connected to a second connection point symmetrical to the first connection point on the negative signal line, and the other end of which is connected to a reference terminal having a second reference voltage.

[0011] In an embodiment of the first aspect, the analog-to-digital conversion circuit includes a power supply terminal, a ground terminal, and a conversion reference input terminal; the power supply terminal is connected to a voltage source, the ground terminal is grounded, and the conversion reference input terminal is connected to a decoupling filter circuit, which includes an RC filter or a capacitor filter circuit.

[0012] In an embodiment of the first aspect, the preprocessing circuit further includes: an electrostatic discharge (ESD) protection unit connected between the thermocouple interface and ground; an input impedance matching unit connected to the ESD protection unit for matching the input impedance of the thermocouple element; and a filtering unit connected to the input impedance matching unit and the analog-to-digital conversion circuit; wherein the connection point between the disconnection detection circuit and the signal line is located after the ESD protection unit and before the input impedance matching unit.

[0013] In a first aspect embodiment, the K-type thermocouple element is configured in a probe end for probing into the food being baked; the temperature measuring device further includes: an interactive component for allowing a user to set baking mode information including food type and grill type; a memory for storing: first associated data including each food type and its associated preset cooking temperature value; second associated data including each grill type and its associated residual heat correction coefficient; and third associated data between multiple sets of preset conditions constructed based on average temperature rise rate and temperature rise rate fluctuation range and associated temperature measuring condition information and basic residual heat value; the temperature measuring condition information includes probe end probing state information of the food being baked, and food thickness level information when the probing state is in place; and an embedded processor, coupled to the interactive component and the memory, for executing: according to the user-selected baking mode information... The system determines the current type of food to be baked and the current type of baking utensils. Based on the target temperature measurement data obtained over a period of time, it calculates the average temperature rise rate and the temperature rise rate fluctuation range, and matches the probe insertion status information in the third associated data according to the average temperature rise rate and the temperature rise rate fluctuation range. In response to determining that the probe is in place in the current food to be baked according to the probe insertion status information, it obtains the thickness level information and basic residual heat value of the current food to be baked in the third associated data. Based on the current type of baking utensils, it determines the residual heat correction coefficient in the second associated data, and corrects the basic residual heat value according to the residual heat correction coefficient to obtain the corrected residual heat value. It subtracts the corrected residual heat value from the preset cooking temperature value associated in the first associated data according to the current type of food to obtain the target cooking temperature value, and outputs a prompt signal when the target temperature measurement value meets the conditions for taking the food out of the oven that include the target cooking temperature value.

[0014] A second aspect of this disclosure provides a thermometer including a temperature measuring device as described in any one of the first aspects.

[0015] A third aspect of this disclosure provides a baking appliance, comprising: a temperature measuring device as described in any one of the first aspects; or a thermometer as described in the second aspect.

[0016] As described above, this disclosure provides a temperature measuring device, thermometer, and baking oven for use in baking. The circuit includes: a K-type thermocouple element; a preprocessing circuit; and an analog-to-digital converter (ADC) circuit connected to the preprocessing circuit to convert the preprocessed thermocouple signal into a temperature measurement digital signal. The ADC circuit allows data output in two's complement format. An ambient temperature sensor collects the cold junction temperature signal of the thermocouple element. An embedded processor obtains the temperature measurement signal value and the cold junction temperature signal value, and after cold junction compensation, converts them to obtain a target temperature measurement value. This process includes: obtaining the temperature measurement digital sample value and the cold junction signal sample value respectively; determining the sign direction of the temperature measurement value based on the temperature measurement digital sample value; determining the cold junction compensation calculation method based on the sign direction; calculating the compensated temperature measurement signal value and the cold junction temperature signal value obtained from the sample value using the cold junction compensation calculation method; and filtering the compensated temperature measurement value to obtain the target temperature measurement value. The K-type thermocouple's high-temperature resistance solves the problem of high-temperature damage and failure of the temperature probe, and, combined with automated cold junction compensation and filtering, obtains accurate temperature measurement results. Attached Figure Description

[0017] Figure 1 A schematic diagram of a circuit module for a temperature measuring device for an oven is shown in one embodiment of this disclosure.

[0018] Figure 2 A schematic diagram of a disconnection detection circuit in one embodiment of this disclosure is shown.

[0019] Figure 3 A schematic diagram of the preprocessing circuit module is shown in one embodiment of this disclosure.

[0020] Figure 4 A schematic diagram of the circuit principle of a temperature measuring device for baking utensils is shown in one embodiment of this disclosure.

[0021] Figure 5 A schematic diagram of the filtering process in one embodiment of this disclosure is shown.

[0022] Figure 6 A schematic diagram of the circuit module of the temperature measuring device is shown in yet another embodiment of this disclosure.

[0023] Figure 7 This diagram illustrates the data flow principle of the unbaked notification function in one embodiment of the present disclosure.

[0024] Figure 8 A flowchart illustrating a method for notifying customers of the oven's output in one embodiment of this disclosure is shown. Detailed Implementation

[0025] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the information disclosed herein. This disclosure can also be implemented or applied through other different specific embodiments, and various details in this disclosure can be modified or changed according to different viewpoints and application modules without departing from the spirit of this disclosure. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this disclosure can be combined with each other.

[0026] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings, so that those skilled in the art to which this disclosure pertains can readily implement it. This disclosure may be embodied in many different forms and is not limited to the embodiments described herein.

[0027] In this disclosure, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic represented in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. Furthermore, the specific features, structures, materials, or characteristics represented may be combined in any suitable manner in any one or a group of embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples represented in this disclosure, as well as the features of those different embodiments or examples.

[0028] Furthermore, the terms "first" and "second" are used for illustrative purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the representation of this disclosure, "a set" means two or more, unless otherwise explicitly specified.

[0029] For the purpose of clarity, devices unrelated to the description are omitted, and the same or similar components throughout the specification are given the same reference numerals.

[0030] Throughout this specification, when it is said that a device is "connected" to another device, this includes not only "direct connection" but also "indirect connection" by placing other components in between. Furthermore, when it is said that a device "comprises" a certain constituent element, unless otherwise stated otherwise, this does not exclude other constituent elements, but rather implies that other constituent elements may be included.

[0031] While the terms first, second, etc., are used in some examples herein to refer to various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, first interface and second interface, etc., are used. Furthermore, as used herein, the singular forms “a,” “an,” and “the” are intended to also include the plural forms unless the context indicates otherwise. It should be further understood that the terms “comprising,” “including,” indicate the presence of the stated feature, step, operation, element, module, item, kind, and / or group, but do not exclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, modules, items, kinds, and / or groups. The terms “or” and “and / or” as used herein are interpreted as inclusive, or mean any one or any combination thereof. Thus, “A, B, or C” or “A, B, and / or C” means “any one of: A; B; C; A and B; A and C; B and C; A, B, and C.” Exceptions to this definition will only occur if the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.

[0032] The technical terms used herein are for reference only to specific embodiments and are not intended to limit the scope of this disclosure. The singular form used herein includes the plural form unless the statement explicitly indicates otherwise. The word "comprising" as used in this specification means to specify a particular characteristic, region, integer, step, operation, element, and / or component, and does not exclude the presence or addition of other characteristics, regions, integers, steps, operations, elements, and / or components.

[0033] Although not explicitly defined, all terms, including technical and scientific terms used herein, shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Terms defined in commonly used dictionaries shall be further interpreted as having a meaning consistent with the relevant technical literature and the message of the present disclosure, and shall not be over-interpreted as having an ideal or overly formulaic meaning unless otherwise defined.

[0034] Currently, temperature measurement in grilling appliances such as electric stoves, teppanyaki grills, pizza ovens, and outdoor barbecue grills often uses temperature sensing components based on PT1000 platinum resistance thermometers. However, this temperature measurement solution has significant drawbacks in practical use, exhibiting poor practicality and reliability. For example, when barbecue equipment is operating, food grease easily drips into the oil collection tray, which can easily ignite upon contact with high temperatures, producing an open flame. The PT1000 platinum resistance thermometer's exposed temperature sensing end and sensing wire are highly susceptible to being burned by the open flame, causing the sensor to malfunction and affecting normal user operation. Furthermore, the high cost of platinum metal leads to high production and replacement costs for the sensing end, impacting economic efficiency.

[0035] Therefore, this disclosure provides a temperature measuring device for baking utensils, which replaces the PT1000 platinum resistance thermometer with a more heat-resistant and oxidation-resistant K-type thermocouple element to construct the circuit, and is combined with signal processing with cold junction compensation and filtering to improve the accuracy of the obtained temperature measurement results.

[0036] like Figure 1 The diagram shows a circuit module schematic of a temperature measuring device 100 for a baking oven according to an embodiment of the present disclosure.

[0037] exist Figure 1 The temperature measuring device 100 includes: a thermocouple element 110, a preprocessing circuit 120, a signal line 130, an analog-to-digital conversion circuit 140, an embedded processor 150, and an ambient temperature sensor 160.

[0038] The thermocouple element 110 is type K. Type K thermocouples acquire temperature based on the Seebeck thermoelectric effect. Exemplarily, the thermocouple element 110 can be composed of a nickel-chromium positive electrode conductor and a nickel-silicon negative electrode conductor, with the two ends fused together to form a hot junction and a cold junction, respectively. The hot junction can be placed in the high-temperature region of the oven (for example, in a temperature probe, which can be implemented as a probe, probe rod, or probe depending on the placement requirements), and the cold junction is placed in a normal temperature reference region. By acquiring the thermocouple signal and combining it with cold junction temperature compensation calculations, the real-time temperature inside the oven can be calculated.

[0039] The K-type thermocouple element 110 has a temperature resistance of up to 1300℃, which is much higher than the 550℃ of PT1000. Therefore, it is suitable for open flame high-temperature scenarios when baking and is not prone to failure.

[0040] The preprocessing circuit 120 is electrically connected to the thermocouple element for receiving thermocouple signals and performing preprocessing. As an example, the preprocessing circuit 120 may include a thermocouple interface 121, which is electrically connected to the thermocouple element 110 to receive thermocouple signals. In some embodiments, the thermocouple interface 121 may be implemented as a plug-in interface, facilitating connection to or disconnection from the thermocouple element 110. For a type K thermocouple, its thermocouple signal includes a pair of voltage signals output from its positive and negative leads (connected to nichrome and nisilicon, respectively). These voltage signals are differential signals, and the differential voltage value between them can be used to calculate the measured temperature signal value. Correspondingly, the thermocouple interface 121 may have a pair of positive and negative terminals connected to the positive and negative terminals of the preceding thermocouple element 110 to receive thermocouple signals. Furthermore, the positive and negative terminals of the thermocouple interface 121 are also connected to a subsequent signal line 130 to transmit the thermocouple signal to the downstream stage. Specifically, the signal line 130 includes a positive signal line 131 and a negative signal line 132, with the positive terminal of the thermocouple interface 121 connected to the positive signal line 131 and the negative terminal connected to the negative signal line 132.

[0041] The analog-to-digital conversion circuit 140 is connected to the stage following the preprocessing circuit and is used to convert the preprocessed thermocouple signal into a temperature measurement digital signal. As an example, the analog-to-digital conversion circuit 140 is connected to the stage following the preprocessing circuit 120 in the signal line 130. In some embodiments, the analog-to-digital conversion circuit 140 can be implemented based on an analog-to-digital converter (ADC) chip.

[0042] Specifically, the analog-to-digital converter circuit 140 includes a differential input interface 141. The differential input interface 141 includes a differential positive input terminal 1411 connected to the positive signal line 131 and a differential negative input terminal 1412 connected to the negative signal line 132. The analog-to-digital converter circuit 140 calculates a differential voltage value based on the differential positive input terminal 1411 and the differential negative input terminal 1412, and performs analog-to-digital conversion accordingly to obtain a temperature measurement digital signal. Furthermore, the analog-to-digital converter circuit 140 also includes an output interface 142 for outputting the temperature measurement digital signal, so that a measured temperature signal value can be obtained from the temperature measurement digital signal.

[0043] In some embodiments, the output interface 142 may be connected to an embedded processor 150 to obtain a measured temperature signal value based on the measured digital temperature signal. In some embodiments, the embedded processor 150 may be implemented as a microprocessor unit (MCU), a digital signal processor (DSP), or a system-on-a-chip (SoC), etc.

[0044] The ambient temperature sensor 160 is communicatively connected to the embedded processor 150 and is used to acquire the cold junction temperature signal of the thermocouple element for cold junction compensation of the measured temperature value corresponding to the measured temperature signal. Specifically, the thermocouple is measured at a standard temperature (e.g., 0°C) at the cold junction. However, during measurement, the cold junction is usually below the ambient temperature, resulting in a deviation between the cold junction temperature and the standard temperature. This reduces the thermoelectric potential difference, leading to inaccurate measurements and errors. To reduce these errors, the temperature value measured by the ambient sensor can be used as the cold junction temperature value for cold junction compensation to eliminate the measurement error caused by the deviation. In some embodiments, a mapping relationship (such as a formula or lookup table) between the ambient temperature value of the cold junction and the compensation value of the measured temperature value can be pre-established. The compensation value corresponding to the measured ambient temperature value can then be obtained through this mapping relationship for compensating the measured temperature value, resulting in a compensated measured temperature signal value. In some embodiments, the ambient temperature sensor 160 can be implemented as an NTC thermistor, and can be attached to or positioned close to the cold junction.

[0045] In some embodiments, the analog-to-digital conversion circuit 140 may further include a power supply terminal, a ground terminal, and a conversion reference input terminal. The power supply terminal is connected to a voltage source, the ground terminal is grounded, and the conversion reference input terminal is used to receive an external reference voltage signal as a reference for the analog-to-digital conversion (ADC). Optionally, the conversion reference input terminal may be connected to a decoupling filter circuit to filter interference from the external reference voltage signal, ensuring the accuracy of the analog-to-digital conversion. As an example, the decoupling filter circuit may include an RC filter or a capacitor filter circuit.

[0046] Optionally, the thermocouple element 110 may be disconnected from the signal line 130, for example, by becoming detached from the thermocouple interface 121. Therefore, the preprocessing circuit 120 may further include a disconnection detection circuit 125, which, in response to detecting a disconnection of the signal line 130 from the thermocouple element 110, changes the voltage on the differential positive input terminal 1411 and / or the differential negative input terminal 1412, so that the differential voltage value is at a disconnection voltage value indicating a disconnection.

[0047] Please refer to Figure 2 The diagram shown illustrates the structure of a disconnection detection circuit 125 in one embodiment of this disclosure.

[0048] exist Figure 2 In the circuit, the disconnection detection circuit 125 includes a first reference voltage unit 1251 and a second reference voltage unit 1252.

[0049] The first reference voltage unit 1251 includes a resistor divider circuit 12511 connected between the first voltage source Vcc1 and ground. Its voltage division point is connected to the first connection point in the positive signal line 131 to set the first reference voltage. Specifically, the voltage source, according to the voltage division ratio determined by the resistor divider circuit 12511, can output a stable first reference voltage at the voltage division point, so that the voltage on the positive signal line 131 is clamped to the first reference voltage. For example, the voltage provided by the voltage source is, for example, 5V, and the first reference voltage is 5*aV obtained according to the voltage division ratio a. If a = 1 / 2, then the first reference voltage is 2.5V. For example, the resistor divider circuit 12511 may include two or more resistors connected in series, and the connection point between the resistors can lead to the voltage division point. Exemplarily, Figure 2 The image shows the third resistor 125111 and the fourth resistor 125112 connected in series.

[0050] The second reference voltage unit 1252 includes a fifth resistor 12521, one end of which is connected to a second connection point symmetrical to the first connection point on the negative signal line 132, and the other end is connected to a reference terminal having a second reference voltage. This resistor is used to guide the second reference voltage to the second connection point in response to the disconnection, thereby changing the voltage of the differential negative input terminal 1412. In some embodiments, the reference terminal may be connected to a second voltage source Vcc2, having a second reference voltage, such as 5V. In other embodiments, the reference terminal may be grounded, providing ground voltage as the second reference voltage.

[0051] When thermocouple element 110 is not disconnected, the voltage signal received from the negative signal line 132 at the negative input terminal comes from the negative pin of thermocouple element 110. This provides a voltage signal within the normal voltage difference between the second connection point and the first reference voltage at the first connection point, allowing the differential voltage value to be used for normal calculation of the measured temperature signal value. However, if thermocouple element 110 is disconnected, the voltage on the negative signal line 132 changes to the second reference voltage (e.g., 5V or 0V). The voltage difference between the first reference voltage and the second reference voltage is then -2.5V (2.5V-5V=-2.5V) or 2.5V (2.5V-0V=2.5V).

[0052] The voltage difference after the disconnection change can set the differential voltage value received by the differential input interface 141 as the disconnection voltage value. The signal value (also called the signal value) of the temperature measurement digital signal converted from the disconnection voltage value can be transmitted to the back-end embedded processor 150 to indicate the disconnection. As an example, the signal value may correspond to the upper limit of the temperature measurement range or exceed the upper limit.

[0053] It is worth mentioning that, Figure 2The implementation of the disconnection detection circuit 125 shown is only an example. Other circuit implementations that can change / switch the voltage in the introduced signal line in response to disconnection can also be applied here and are within the scope of protection of this disclosure, and are not limited to the illustration.

[0054] like Figure 3 The diagram shows a schematic of the circuit modules of the preprocessing circuit 120 in one embodiment of the present disclosure.

[0055] The preprocessing circuit 120 also includes an electrostatic protection unit 122, an input impedance matching unit 123, and a filtering unit 124.

[0056] For example, the electrostatic discharge protection unit 122 is connected between the thermocouple interface 121 and ground. In some embodiments, the electrostatic discharge protection unit 122 may include a pair of transient suppression diodes, which are respectively connected to the positive signal line 131 and the negative signal line 132 to ground.

[0057] Exemplarily, the input impedance matching unit 123 is connected to the electrostatic protection unit 122 to match the input impedance of the thermocouple element 110. In some embodiments, the input impedance matching unit 123 includes a pair of resistors, namely a first resistor 1231 and a second resistor 1232, which are connected in series in the positive signal line 131 and the negative signal line 132, respectively. It should be noted that the pair of resistors have the same resistance value and are symmetrically arranged in the two signal lines of the signal line 130 in the same series configuration.

[0058] Exemplarily, the filtering unit 124 is connected to the input impedance matching unit 123 and the analog-to-digital conversion circuit 140. In some embodiments, the filtering unit 124 may include a first capacitor 1241, a second capacitor 1242, and a third capacitor 1243. The first capacitor 1241 and the second capacitor 1242 are a pair, having the same capacitance value, and are symmetrically connected to the positive signal line 131 and the negative signal line 132, respectively, and grounded. The third capacitor 1243 may be connected across the positive signal line 131 and the negative signal line 132. The first capacitor 1241, the second capacitor 1242, and the third capacitor 1243, together with the pair of resistors in the preceding stage, constitute an RC low-pass filter. Specifically, the first resistor 1231 and the first capacitor 1241 are connected in parallel in the positive signal line 131 to form an RC low-pass filter, and the second resistor 1232 and the second capacitor 1242 are connected in parallel in the negative signal line 132 to form an RC low-pass filter, which can filter differential-mode interference. The third capacitor 1243 is connected in parallel with the first resistor 1231 and the second resistor 1232, and can be used to suppress common-mode interference.

[0059] Optionally, the connection point between the disconnection detection circuit 125 and the signal line 130 can be located after the electrostatic protection unit 122 and before the input impedance matching unit 123, so that the disconnection of the thermocouple element 110 can be detected as early as possible after electrostatic protection. Of course, it can also be changed as needed.

[0060] For example Figure 4 The diagram shows a schematic circuit diagram of a temperature measuring device 100 for a baking oven according to an embodiment of the present disclosure.

[0061] In this embodiment, the temperature measuring device 100 includes: devices U1 and U2; transient suppression diodes D1 and D2; resistors R1, R2, R3, R4, R5, and R6; and capacitors C1, C2, C3, C4, and C5.

[0062] Device U1 is an ADC chip, which can be used as the analog-to-digital conversion circuit. As an example, U1 includes terminals such as IN+, IN-, VDD, GND, REFIN, REFOUT, OUT, and SCLK. IN+ and IN- serve as the differential positive input terminal 1411 and differential negative input terminal 1412, VDD is the power supply terminal connected to a voltage source (in this example, +5V), and GND is the ground terminal. OUT is the output terminal, and SCLK is the clock terminal for connecting to the embedded processor 150. REFIN is the conversion reference input terminal, and REFOUT is the conversion reference output terminal, which can be left floating.

[0063] Device U2 is a connector and can be used as the thermocouple interface 121.

[0064] Transient suppression diodes D1 and D2 can constitute the electrostatic discharge protection circuit. One end of D1 is connected to the positive signal line 131, and the other end is grounded. One end of D2 is connected to the negative signal line 132, and the other end is grounded.

[0065] Resistors R1 and R2 can form the input impedance matching unit 123. R1 is connected in series in the positive signal line 131, and R2 is connected in series in the negative signal line 132.

[0066] Resistors R3, R4, and R5 constitute the disconnection detection circuit 125. R3 and R4 form a resistor voltage divider circuit 12511, applying a first reference voltage of 5V*R4 / (R3+R4) to the first connection point A in the positive signal line 131. For example, if R3=R4, the first reference voltage at the voltage divider point is 2.5V. R5 connects to the second connection point B of the negative signal line 132 and the reference terminal. The second connection point B is symmetrical to the first connection point A. That is, A is between D1 and R1, and B is between D2 and R2. In this embodiment, the reference terminal can be grounded to make the second reference voltage 0V. Specifically, one end of R3 is connected to a voltage source, and the other end is connected to one end of R4 and the first connection point; the other end of R4 is grounded. One end of R5 is connected to the second connection point, and the other end is connected to the reference terminal.

[0067] The filter unit 124 includes C1, C2, and C3, which, together with resistors R2 and R1, form an RC low-pass filter. One end of C1 is connected to the positive signal line 131, and the other end is grounded. One end of C2 is connected to the negative signal line 132, and the other end is grounded. C3 is connected across R1 and R2, bridging the positive signal line 131 and the negative signal line 132.

[0068] C4, R6, and C5 constitute a decoupling filter circuit 180 connected to REFIN. Specifically, one end of C4 is connected to a voltage source providing a reference voltage (e.g., +5V) and one end of R6, while the other end is grounded. The other end of R6 is connected to one end of C5 and REFIN, and the other end of C5 is grounded. C4, R6, and C5 form a π-shaped filter for CRC. In other embodiments, only one or more parallel capacitors may be used, such as C4 and C5 in parallel or a single capacitor.

[0069] IN+ is connected to the positive signal line 131 after C1, and IN- is connected to the negative signal line 132 after C2. U1 calculates the difference between the voltage values ​​of IN+ and IN- to obtain the differential voltage value, and converts the differential voltage value into an analog-to-digital signal to form a temperature measurement digital signal, which is output from the OUT terminal.

[0070] The OUT terminal can be connected to an embedded processor 150, which can be connected to an ambient temperature sensor 160. The processor 150 calculates the measured temperature signal value based on the measured temperature digital signal and calculates the cold junction temperature signal value based on the cold junction temperature signal of the ambient temperature sensor 160. The processor 150 then performs cold junction temperature compensation on the measured temperature signal value to obtain the final compensated measured temperature signal value.

[0071] The embedded processor 150 receives the temperature measurement digital signal and the cold junction temperature signal from the analog-to-digital conversion circuit and the ambient temperature sensor, and performs cold junction compensation and filtering to obtain accurate temperature measurement results.

[0072] In some embodiments, the embedded processor 150 can obtain the temperature measurement digital sampling value and the cold junction temperature value based on the temperature measurement digital signal and the cold junction temperature signal, respectively. For example, the embedded processor 150 can directly extract the AD sampling value, i.e., the temperature measurement digital sampling value, from the temperature measurement digital signal. If the cold junction temperature signal is an analog signal, the embedded processor 150 may have an analog-to-digital converter to convert it into a digital signal to obtain the cold junction temperature value; alternatively, the ambient temperature sensor may have an integrated analog-to-digital converter or be connected to the embedded processor 150 to transmit the cold junction temperature signal in digital form, and the embedded processor 150 can directly extract the cold junction signal sampling value from the digital cold junction temperature signal.

[0073] In some embodiments, the embedded processor 150 may determine the sign direction of the temperature measurement value corresponding to the temperature measurement digital sample value and / or the disconnection event of the thermocouple element based on a comparison of the temperature measurement digital sample value with at least one range boundary threshold in the range of the sampling value of the analog-to-digital conversion circuit and / or the disconnection event of the thermocouple element.

[0074] Specifically, the analog-to-digital converter circuit 140 may include an ADC chip capable of outputting two's complement format data, enabling the temperature measurement range of the ADC circuit 140 to cover both positive and negative bidirectional temperature measurements. Taking the ADC chip that outputs 24-bit two's complement format data as an example, the positive full-scale sampling value is +8,388,607 (0x7FFFFF), and the negative full-scale sampling value is -8,388,608 (0x800000). When the temperature measurement sampling value output by the ADC chip is 0x7FFFFF, the corresponding input voltage is +Vref / (2*gain). If Vref is +5V and the gain is 1, the range corresponds to an input voltage range of ±2.5V; if the gain is 128, the range corresponds to an input voltage range of approximately ±19.5mV.

[0075] In some embodiments, the full-scale temperature measurement digital sample value output by the analog-to-digital converter 140 (e.g., 0x7FFFFF) can be used as a preset threshold for determining the zero point from the positive range to the negative range. By comparing the temperature measurement digital sample value of the analog-to-digital converter 140 with the preset threshold, the sign direction of the corresponding temperature measurement value can be determined. For example, when the temperature measurement digital sample value is less than or equal to 0x7FFFFF, it indicates that the temperature measurement value is positive; or, when the temperature measurement digital sample value is greater than 0x7FFFF, it indicates that the temperature measurement value is negative.

[0076] In some embodiments, the disconnection voltage value may correspond to a full-scale sampling value setting of the analog-to-digital conversion circuit 140, such as a positive full-scale sampling value (0x7FFFFF) or a negative full-scale sampling value (0x800000). The embedded processor 150 can determine the occurrence of a thermocouple element disconnection event by judging that the received temperature measurement digital sampling value is a continuously stable range boundary threshold, or that the temperature measurement digital sampling value is a range boundary threshold and the temperature of the range boundary threshold in the actual scenario is unlikely to be reached.

[0077] Therefore, by comparing the digital temperature sample value with the range boundary threshold of the sample value range of the analog-to-digital conversion circuit, the sign direction of the temperature measurement value can be represented, and the disconnection event of the thermocouple element can be detected, achieving multiple benefits in one go.

[0078] Further, based on the sign direction, a cold junction compensation calculation method is determined corresponding to the temperature measurement signal value and the cold junction temperature signal value. The compensated temperature signal value, after being compensated by the cold junction temperature signal value, is calculated using this method. The temperature measurement signal value and the cold junction temperature signal value are obtained by converting the temperature measurement digital sampling value and the cold junction temperature value, respectively. In some embodiments, the temperature measurement signal value and the cold junction temperature signal value can be in the form of voltage values. The AD value can be converted into a voltage value based on the proportional relationship between the sampling value range of the temperature measurement range and the voltage value range. Temperature values ​​can be converted into voltage values, or voltage values ​​can be converted into temperature values, by looking up a calibration table, thus facilitating compensation calculations.

[0079] The cold junction compensation calculation methods differ depending on the sign direction of the measured temperature signal and the cold junction temperature signal. For example, suppose the measured temperature signal is Vol1, the cold junction temperature signal is Vol2, and the compensated temperature signal is Vol3. If the sign of the measured temperature value is positive, the cold junction compensation calculation method is Vol3 = Vol11 + Vol2. Alternatively, if the sign of the measured temperature digital sample value is negative, the cold junction compensation calculation method is Vol3 = Vol2 - Vol11. This ensures that correct cold junction compensation is obtained regardless of whether Vol1 corresponds to a positive or negative value. Furthermore, the corresponding compensated temperature value can be obtained by looking up the calibration table based on Vol3.

[0080] It should be noted that the above cold junction compensation calculation method comes from the thermocouple temperature measurement calculation formula: EAB(T, 0) = EAB(T, T0) + EAB(T0, 0), where the values ​​of EAB(T, T0), EAB(T0, 0), and EAB(T, 0) correspond to Vol1, Vol2, and Vol3 respectively. Here, EAB(T, T0) represents the thermoelectric potential of the thermocouple at the hot junction temperature T and the cold junction temperature T0, EAB(T, 0) is the thermoelectric potential at the hot junction temperature T and the cold junction temperature 0℃, and EAB(T0, 0) is the thermoelectric potential at the cold junction temperature T0 and the hot junction temperature 0℃. For example, when measuring temperature T with a thermocouple, the cold junction is in an ambient temperature environment T0. If the measured temperature signal value (thermoelectric potential) EAB(T, T0) = 1.999mV, and based on the positive sign of the sampled value, and an environmental sensor measures T0 = 21℃... Assuming we consult the calibration table for this type of thermocouple, we find that the cold junction EAB(21,0) = 0.832mV. Therefore, we have EAB(T,0) = EAB(T,21) + EAB(21,0) * 1.999 + 0.832 = 2.831 (mV). Looking back at the calibration table, the hot junction temperature corresponding to 2.831mV is T = 68℃. If the sign is negative, then EAB(T,T0) = -Vol1, and EAB(T0,0) is positive, making EAB(T,0) = Vol3 = Vol2 + (-Vol1) = Vol2 - Vol1.

[0081] Furthermore, the target temperature value is obtained based on the filtering process of the compensated temperature value.

[0082] like Figure 5 The diagram shown illustrates a flowchart of the filtering process in one embodiment of this disclosure.

[0083] exist Figure 5 The process includes:

[0084] Step S501: Obtain the current compensated temperature measurement value and the historical compensated temperature measurement value, and perform smoothing filtering to obtain the smoothed filtered value of the current compensated temperature measurement value.

[0085] In some embodiments, the smoothing filter includes, but is not limited to, median filtering. Median filtering has a good ability to suppress occasional abrupt changes with amplitudes significantly greater than the inherent noise of the system (e.g., sudden jumps in compensated temperature readings caused by open flame radiation, start-up transients, or oil droplets splashing onto the temperature probe). In other embodiments, the smoothing filter can also be implemented as mean filtering, weighted median filtering, recursive median filtering, or other filtering forms capable of suppressing occasional abrupt changes.

[0086] Let the current compensated temperature measurement value be E. k Then E kThe historical compensated temperature measurement value E is the same as the previously obtained preset quantity (e.g., 3, 5, etc.). k-1 E k-2 ... and so on, and take the median E of the set. midk This is the result of the median filtering.

[0087] Step S502: Compare the difference between the current compensated temperature measurement value and the smoothed filter value to obtain the noise value.

[0088] For example, the E k With median E midk The difference is calculated to obtain the noise value.

[0089] Step S503: Determine whether the noise value is greater than a preset threshold.

[0090] In some embodiments, since smoothing filtering has eliminated occasional abrupt changes, it can be determined whether the inherent noise of the system exceeds the line requiring adjustment by comparing the noise value with a preset threshold. For example, the noise value can be set within the range of 0.1℃~0.3℃, 0.3℃~0.5℃, etc.

[0091] Step S504: Increase / decrease the observed noise covariance according to whether the noise value is greater than or not greater than a preset threshold.

[0092] The observation noise covariance is used in a Kalman filter. The observation noise covariance (usually denoted as the R matrix) is one of the parameters of the Kalman filter, which determines the degree of trust the Kalman filter has in the sensor measurements. The larger the R is, the smaller the Kalman gain, and the more the filter trusts the prediction model; conversely, the smaller the R is, the more it trusts the measurements.

[0093] When the noise value is greater than the preset threshold, the observed noise covariance is reduced. Conversely, when the noise value is less than or equal to the preset threshold, the observed noise covariance is reduced.

[0094] Step S505: The current compensated temperature value is filtered by the Kalman filter according to the observation noise covariance to obtain the current target temperature value.

[0095] Specifically, the noise level is estimated by comparing the current compensated temperature value with the median, and the observation noise covariance of the Kalman filter is adjusted accordingly to suppress the noise. It's worth noting that using a smoothing filter and estimating the noise before adjusting the observation noise covariance, compared to directly applying the Kalman filter, uses the actual raw value as a reference, rather than relying on the Kalman filter value. This allows for the differentiation between actual temperature rise and sensor noise, and also improves the hysteresis of the Kalman filter itself.

[0096] The application of the temperature measuring device 100 in the oven according to the embodiments of this disclosure can be designed according to requirements. In some embodiments, the K-type thermocouple element can be placed in a temperature-sensing end inserted into the open flame area of ​​the oven to detect the heating temperature of the oven. In other embodiments, the thermocouple element can also be configured in a temperature-sensing end inserted into the food being baked (e.g., implemented as a "temperature probe"), which can be used to determine the appropriate doneness of the food based on the detected temperature. As an example, this disclosure considers the type of food being baked and the type of oven to obtain the appropriate doneness of the food. Different types of food have different temperature requirements for different degrees of doneness, and considering the influence of the amount of residual heat when the food is removed from the oven on the degree of doneness achieved when the food is edible, it is also necessary to consider the influence of the heat storage capacity of different types of ovens on the residual heat of the food, and it is also necessary to consider the different amounts of residual heat accumulated corresponding to different thicknesses of the food.

[0097] For example, the grilled items can be of various types, such as categorized by meat or vegetables, or by type of meat, vegetables, offal, bean products, or other types, or by different types of animal meat (beef, lamb, chicken). Additionally, they can be categorized based on different parts of the animal meat, different degrees of doneness, etc. That is, the categorization of grilled items includes one or a combination of: meat / vegetarian, category, different animal species / parts / degrees of doneness, etc.

[0098] For example, the grilling equipment can be divided into different types, including but not limited to electric stoves, teppanyaki grills, outdoor barbecue grills, etc.

[0099] like Figure 6 The diagram shows a schematic of the circuit module of the temperature measuring device in another embodiment of this disclosure.

[0100] exist Figure 6 In, in combination Figure 1 The embedded processor 150 and the temperature measuring device 100 in the embodiment may further include an interaction component 160 and a memory 170. Figure 6 Omitted Figure 1 Other circuit components besides the embedded processor 150.

[0101] The interactive component 160 is used for users to set baking mode information including the type of food to be baked and the type of baking utensil. In some embodiments, the type of food to be baked and the type of baking utensil can be selected from the various listed above and implemented in the actual product.

[0102] In some embodiments, the interaction component 160 may be implemented as a physical / virtual operation key / button or other form of input component for user operation to set the baking mode information. For example, the physical operation key may be in the form of multiple buttons corresponding to different types of baked goods / grills, or it may be in the form of a slider / knob with settings corresponding to different types of baked goods / grills.

[0103] In some embodiments, the temperature measuring device 100 may include a wired / wireless communication (e.g., Bluetooth, WiFi) communicator 180 for communicating with external devices. The communicator 180 may also be used as the interaction component 160. For example, the communicator 180 may wirelessly communicate with a mobile terminal to receive the baking mode information set and sent by the user on a companion app running on the mobile terminal. The communicator 180 may also be used to transmit the target temperature value measured by the temperature measuring device 100 to an external device.

[0104] In some embodiments, the memory 170 is used to store first associated data, second associated data, and third associated data. In some embodiments, the memory 170 may be integrated into the embedded processor 150, or it may be located outside the embedded processor 150 and communicatively connected to it. In some embodiments, the memory 170 may be implemented as at least one of flash memory, EEPROM, eMMC, or a combination of off-chip RAM and non-volatile memory, without limitation herein.

[0105] The first associated data relates to each type of baked item and its associated preset cooking temperature value. Therefore, based on the selected type of baked item, the associated preset cooking temperature value can be matched within the first associated data. As an example, the preset cooking temperature value can be set as the target temperature at which the baked item, after being removed from the heat source and left to stand, completes residual heat retention and reaches the target doneness, taste, or food safety threshold. The preset cooking temperature value can be determined based on actual measurements or experience.

[0106] In some embodiments, the first associated data can be presented in the form of a table, and a lookup table method can be used to determine the preset ripening temperature value. Preferably, the first associated data may also include the minimum steady-state maintenance time required to reach the desired ripeness at the preset ripening temperature value. The minimum steady-state maintenance time can also be determined based on actual measurements or experience. As an example, the first associated data may be in the form of Table 1:

[0107] Table 1 Example of First Related Data

[0108]

[0109] The preset cooking temperature and minimum steady-state maintenance time mentioned in Table 1 are only examples. The specific values ​​can be adjusted according to one or more of the actual type of food being baked, the part of the food, the initial temperature, the taste, and food safety standards.

[0110] The second set of associated data considers the impact of different oven heat storage capacities on the residual heat of baked goods, including each oven type and its associated residual heat correction factor. Therefore, the associated residual heat correction factor can be matched to the second set of associated data based on the selected oven type.

[0111] The residual heat correction coefficient is used to characterize the increase in meat core temperature caused by residual heat that can continue after the heat source stops heating, under different oven cavity heat storage and heat dissipation environments. A larger residual heat correction coefficient indicates a stronger residual heat effect from the oven and a greater temperature rise after the meat is removed from the oven. As an example, the second correlation data can be shown in Table 2 below:

[0112] Table 2. Example of Second Related Data

[0113]

[0114] It should be noted that the above correction factors are related to the heat storage capacity of the oven. Therefore, whether the cavity is sealed or not, the heat dissipation rate, etc., will all affect the magnitude of the correction factor. The specific value of the correction factor can be set based on actual measurements / experience of the oven's cavity structure, heat storage capacity, and heat dissipation characteristics.

[0115] The third associated data includes multiple sets of temperature measurement condition information and basic residual heat values ​​associated with preset conditions constructed based on the average temperature rise rate and temperature rise rate fluctuation range. The temperature measurement condition information includes the probe's insertion status information in the food being grilled, and the thickness level information of the food when the probe is fully inserted. Therefore, based on the measured average temperature rise rate and temperature rise rate fluctuation range, the probe's insertion status information can be determined by matching the third associated data. The insertion status information may include whether the probe has fully penetrated the food. Taking meat as an example, to accurately determine the doneness of the meat, the probe needs to be inserted into the core of the meat to make an accurate judgment. Otherwise, if the probe only penetrates the shallow surface of the food, even if the shallow surface is cooked, it does not mean the whole piece of meat is cooked. Furthermore, the residual heat of the grill has different abilities to heat food of different thicknesses to the desired doneness; therefore, the thickness of the food also needs to be considered. Thinner pieces of meat are easier to heat to the desired doneness using residual heat. An example illustrates the calculation method for the average temperature rise rate and temperature rise rate fluctuation range. In some examples, the temperature rise rate calculation window w can be moved by a preset step size (which can be between 1 and w) on multiple target temperature value data obtained within a periodic duration W to obtain n sets of target temperature values. The temperature rise rate is calculated for each set of target temperature values ​​to obtain the temperature rise rate sequence Slist={S1, S2, ..., Sn}. The average temperature rise rate S̄ is obtained by averaging S1 to Sn, and the temperature rise rate fluctuation range ΔSrange is obtained by iterating through the maximum difference between each pair of S1 to Sn, and the peak temperature rise rate S_peak (which can be used for additional conditions in Table 3) is obtained.

[0116] In this embodiment, the specific insertion position of the temperature probe is determined by utilizing the different temperature change characteristics exhibited by the food at different depths and thicknesses during baking. Specifically, this embodiment uses the average temperature rise rate and the temperature rise rate fluctuation range as indicators to accurately distinguish whether the temperature probe is located in the surface or core layer, thus determining whether the probe has penetrated properly. If it has penetrated properly, the thickness level of the food is determined. The thickness level refers to an approximate thickness, such as thin, standard, or thick. Considering the balance between thickness detection accuracy and cost, this embodiment only makes a rough estimate based on temperature change information. Furthermore, the thickness of the food typically does not need to be overly precise; for example, meat is usually pre-processed into slices, patties, or chunks, so a precise thickness value is not required, only an approximate level. Therefore, it eliminates the need for a separate sensor for precise thickness measurement, reducing product cost and development difficulty.

[0117] The following table 3 illustrates possible forms of third-party related data.

[0118] Table 3. Example of Third-Party Related Data

[0119]

[0120] In Table 3, taking grilled meat as an example, the surface layer is fat and fascia, the core is lean meat, it may also have bones, and the bones may have cavities. Correspondingly, in this example, the in-place penetration state means that the temperature measuring end reaches the lean meat layer of the meat core. The out-of-place penetration state means that the temperature measuring end is located in one of fat, fascia, bone and cavity.

[0121] Therefore, the preset conditions corresponding to the in-place penetration state include that the temperature rise rate fluctuation range is lower than a first preset threshold, and the average temperature rise rate is equal to or higher than a second preset threshold. The temperature rise rate fluctuation range being lower than the first preset threshold indicates that the temperature rise trend is smooth and the embedding depth of the temperature measuring end is qualified. Illustratively, taking meat as an example, the first preset threshold can be exemplified as being in the interval of 2 to 3, or 3 to 4, preferably 3. The average temperature rise rate being equal to or higher than the second preset threshold indicates that the average temperature rise rate will not be too low, thereby characterizing that the temperature measuring end does not detect a part with weak heat conduction, such as bones / bone cavities of meat. Taking meat as an example, the second preset threshold can be exemplified as being in the interval of 0.2 to 0.3 or 0.3 to 0.4, preferably 0.3. Wherein, the thickness grade is negatively correlated with the average temperature rise rate, and the thicker the grilled food is, the slower the temperature rise will be.

[0122] Based on this principle, in some embodiments, the negative correlation between the thickness grade and the average temperature rise rate includes the following several cases.

[0123] When the temperature rise rate fluctuation range is lower than the first preset threshold, and the average temperature rise rate is equal to or higher than the second preset threshold and equal to or lower than a third preset threshold, it is determined that the temperature measuring end reaches the meat core and the grilled food is a thick piece of meat. In some embodiments, the second preset threshold can be exemplified as being in the interval of 0.2 to 0.3 or 0.3 to 0.4, preferably 0.3. The third preset threshold can be exemplified as being in the interval of 1.5 to 2, or 2 to 2.5, preferably 2. Of course, the above preset thresholds are only examples, and can be changed according to actual measurement results. The preset condition in this example can be set as ΔS_range<3, 0.3<S̄<2. The principle is explained in detail below. In this embodiment, three thickness grades "thick", "normal thick" and "thin" are exemplarily set. The temperature rise rate fluctuation range being lower than the first preset threshold indicates that the temperature rise trend is smooth and the embedding depth of the temperature measuring end is qualified; furthermore, in combination with the average temperature rise rate being equal to or higher than the second preset threshold and equal to or lower than the third preset threshold, it illustrates in detail that the meat piece has a large thickness, a long heat conduction path, a relatively slow heat penetration speed inward, and a low average temperature rise rate. Therefore, the highest residual heating base value ΔT_res(base)=x°C (x>y≥z) is configured, the maximum residual heating space for the meat piece is reserved, so that the outgoing temperature can be relatively the lowest, and over-ripening of the meat quality after standing due to residual heating can be avoided.

[0124] If the temperature rise rate fluctuation range is lower than the first preset threshold, and the average temperature rise rate is above the third preset threshold and below the fourth preset threshold (e.g., 6), it is determined that the temperature probe reaches the meat core and the meat being roasted is of normal thickness. Under these preset conditions, the temperature rise rate fluctuation range being lower than the first preset threshold indicates a smooth heating trend and that the base burial depth of the temperature probe is acceptable. Furthermore, the average temperature rise rate being above the third preset threshold and below the fourth preset threshold indicates, in detail, that the meat thickness is medium ("normal thickness" means medium thickness), the heat conduction path is medium, the heat penetration rate is medium, and the average temperature rise rate is medium. Therefore, a medium base residual heat value ΔT_res(base) = y℃ is configured, reserving a relatively medium amount of residual heat for heating the meat, resulting in a relatively medium exit temperature.

[0125] If the temperature rise rate fluctuation range is lower than the first preset threshold and the average temperature rise rate is higher than the fourth preset threshold, it is determined that the temperature probe reaches the meat core and the meat being roasted is a thin slice. Under these preset conditions, the temperature rise rate fluctuation range being lower than the first preset threshold indicates a smooth heating trend and that the temperature probe depth is acceptable; furthermore, the average temperature rise rate being higher than the fourth preset threshold indicates that the meat slice is thin, meaning a short heat conduction path, rapid heat penetration, and a relatively high average temperature rise rate. Therefore, a moderate base residual heat value ΔT_res(base) = z℃ is configured, reserving a relatively minimal amount of residual heat for heating the meat slice, resulting in the highest possible exit temperature.

[0126] In addition, the preset conditions corresponding to the probe not being in place include at least the temperature rise rate fluctuation range being greater than the first preset threshold, such as ΔS_range>3.

[0127] In some embodiments, the preset conditions corresponding to the probe not being in place may include additional conditions besides the temperature rise rate fluctuation range being greater than the first preset threshold, in order to help determine the specific state.

[0128] In some embodiments, additional conditions may include: determining a first non-compliant state when the instantaneous temperature rise rate exceeds a preset upper limit threshold during the periodic duration. Specifically, referring to Table 3, the preset upper limit threshold may be in the range of 7~8 or 8~9, preferably 8. To explain the principle simply, if the temperature probe is buried too deep, the temperature measuring part will be exposed to an open flame or high-temperature hot air. The open flame will cause a sudden temperature surge, resulting in a rapid increase in the temperature rise rate.

[0129] In some embodiments, the additional condition may further include: the average temperature rise rate is lower than a fifth preset threshold between a second preset threshold and a third preset threshold, and the maximum temperature rise rate during the cycle exceeds a sixth preset threshold between a third preset threshold and a fourth preset threshold, thus determining a second incomplete state. The second incomplete state indicates that the probe tip is inserted into the superficial fat / fascia interlayer but not into the core. Exemplarily, the fifth preset threshold may be 0.6~0.8 or 0.8~1, preferably 0.8. The sixth preset threshold may be in the range of 3.5~4 or 4~4.5, preferably 4. To explain the principle simply, because fat has a low specific heat capacity and low thermal conductivity, its temperature exhibits a localized rapid increase, saturation, and then fluctuation.

[0130] In some embodiments, the first, second, and third associated data may also be stored in other forms than tables, such as arrays, as long as they are suitable for the capacity of the memory 170 and the processing speed requirements of the embedded processor 150 in the scenario, and are not limited to the table formats in Tables 1 to 3 above.

[0131] Based on the above, the embedded processor 150 can implement a function to prompt the user when the baked goods reach the desired doneness, thereby improving the user experience by providing optimal doneness information for different baked goods and oven types. Specifically, the embedded processor 150 can obtain the target doneness value based on the baking mode information input by the user through the interaction component 160 and the associated data stored in the memory 170. For example, it can refer to... Figure 7This document presents a data flow diagram illustrating the implementation of the oven exit notification function in one embodiment of this disclosure. In this embodiment, the principle is demonstrated using Tables 1-3 as examples. The user inputs baking mode information, including the type of food to be baked and the type of baking utensils, into the interactive component 160. Based on the type of food to be baked, the preset cooking temperature value T_std is obtained from Table 1 (optionally, the minimum steady-state maintenance time T_min can also be obtained), and based on the type of baking utensils, the residual heat correction coefficient Koven is obtained from Table 2. Furthermore, based on the target temperature measurement data obtained over a periodic period, the average temperature rise rate S̄ and the temperature rise rate fluctuation range ΔS_range are calculated, and the temperature probe is matched and determined in Table 3 to determine whether the probe is in position. When in position, the basic residual heat value ΔT_res(base) corresponding to the thickness level of the food being baked can be obtained. The basic residual heat value ΔT_res(base) is corrected by a correction coefficient to obtain the corrected residual heat value, i.e., ΔT_res(base)*Koven. The preset cooking temperature value is subtracted from the corrected residual heat value T_std-ΔT_res(base)*Koven to obtain the target cooking temperature value. When the target temperature measurement value meets the oven exit conditions including the target cooking temperature value, a prompt signal is output. Further, the prompt signal can be sent to an external device, such as a mobile terminal with a communication connection, through the communicator 180 to trigger a prompt action to the user, such as sound, light, image, or text. In an optional example, the embedded processor 150 can also be connected to a prompt unit 190, which can provide prompts in the form of sound, light, etc., such as a speaker (which may be a buzzer), indicator light, etc. Alternatively, the prompts can be in the form of text or images, in which case the prompt unit 190 can also be a small-sized display screen, etc.

[0132] In some embodiments, the oven exit condition can be set to include only "the target temperature value reaches the target cooking temperature value", that is, the target cooking temperature value ≥ T_std - ΔT_res(base) * Koven. Alternatively, the oven exit condition can also be set to "the target temperature value reaches the target cooking temperature value and remains in a stable state for the minimum duration", etc.

[0133] It is worth noting that the periodic duration is a time window for collecting a set of continuous target temperature values. This time window should not be set too long to avoid errors caused by the average temperature rise rate and its fluctuation range. Preferably, the periodic duration can be determined based on the number of target temperature values ​​required to accurately calculate ΔS_range and S̄. Assuming the single-point acquisition time for a single target temperature value is c milliseconds, and the required preset number of samples is b, the periodic duration can be set to approximately b*c milliseconds. The single-point acquisition time for a single target temperature value can be estimated based on the total time required to obtain the single target temperature measurement from the AD sampling values ​​after cold junction compensation calculation and filtering.

[0134] Based on the above principles, one embodiment of this disclosure can also provide a method for indicating when a component is unpacked, which can be applied to the embedded processor 150. (See reference...) Figure 8 The diagram shown illustrates a flowchart of a method for notifying the oven when it is unbaked, according to one embodiment of this disclosure. It should be noted that... Figure 8 The implementation details in the embodiments have been described in detail in the previous embodiments, and will be briefly described below without being repeated.

[0135] exist Figure 8 The process includes:

[0136] Step S801: Determine the current type of food to be baked and the current type of baking utensils based on the baking mode information selected by the user.

[0137] For example, the baking mode information can be input by the user's local operation or via a communication connection.

[0138] Step S802: Calculate the average temperature rise rate and temperature rise rate fluctuation range based on the target temperature measurement data obtained in a periodic period, and match the probe status information in the third associated data according to the average temperature rise rate and temperature rise rate fluctuation range.

[0139] Step S803: In response to determining that the probe end is in place in the current food being baked based on the probe state information, the thickness level information and basic residual heat value of the current food being baked are obtained in the third associated data.

[0140] For example, based on the average temperature rise rate and the temperature rise rate fluctuation range matched in Table 3, it is determined whether the probe has reached the correct position for the food being baked. When the preset conditions for reaching the correct position are met, the correct position and thickness level are determined. When the correct position is determined, the corresponding basic residual heat value is determined based on the thickness level.

[0141] Step S804: Determine the residual heat correction coefficient based on the current oven type in the second associated data, and correct the base residual heat value according to the residual heat correction coefficient to obtain the corrected residual heat value.

[0142] For example, calculate ΔT_res(base)*Koven to obtain the corrected residual heat value.

[0143] Step S805: Subtract the corrected residual heat value from the preset cooking temperature value associated with the first associated data according to the current type of baked goods to obtain the target cooking temperature value, so as to output a prompt signal when the target temperature value meets the conditions for taking the food out of the oven including the target cooking temperature value.

[0144] For example, the target cooking temperature is obtained by subtracting the corrected residual heat value from the preset cooking temperature value, i.e., T_std - ΔT_res(base) * Koven. Then, each acquired target temperature value is matched against the baking conditions, such as "the target temperature value reaches the target cooking temperature value" or "the target temperature value reaches the target cooking temperature value and remains at the minimum steady-state duration." If a match is found, a prompt message can be output to the user, either locally or at an external communication peer. Upon receiving this prompt, the user can remove the food from the oven, allowing the residual heat to continue heating it to the target cooking temperature. It should be noted that after removing the food from the oven, it can be kept warm, such as wrapped in aluminum foil. The food should be kept away from environments that cause residual heat loss, such as ventilated / cold air or low-temperature environments.

[0145] For example, a user selects "medium-rare beef," "teppanyaki grill," and uses a thick cut of meat. The first preset threshold is set to 3, the second preset threshold is set to 0.3, and the third preset threshold is set to 2.

[0146] From the table, we obtain T_std = 60℃ for meat, Koven = b, and set b = 1.13. Based on the target temperature measurement data over 10 seconds, we calculate ΔS_range = 2.5 < the first preset threshold of 3, and calculate S̄ = 0.9. Since 0.3 < 0.9 < 2, we determine the thickness level as thick meat. We match the associated base residual heat value ΔT_res(base) = x, and set x = 6℃. The target cooking temperature is calculated as 60℃ - 1.13 × 6℃ = 53.22℃.

[0147] Determine if the target measured temperature has reached 53.22℃. If it has, indicate that the food is ready to be removed from the oven.

[0148] In some embodiments, the power supply for the temperature measuring device 100 can be electrically connected to the power supply of the oven, or when it is separate from the oven, the temperature measuring device 100 can be independently powered by a battery. Depending on whether the oven is sealed or open, the power supply method can be varied according to actual needs.

[0149] In the above functions, the target cooked temperature value after residual heat compensation can be estimated and the product should be judged and prompted based solely on the user-input grilling mode information and the target temperature value obtained by the temperature measuring device 100. This eliminates the need for additional sensors (such as vision or depth sensors), resulting in extremely low hardware costs. Furthermore, by updating the entries in the first, second, and third associated data sets, preset conditions can be easily added for new grilled items, new grilling equipment types, or new piercing conditions without modifying the main judgment logic, demonstrating strong scalability and scenario adaptability. Moreover, the condition judgments are based on relative temperature rise rates rather than absolute temperature values. Therefore, regardless of oven temperature, initial meat temperature, or changes in ambient temperature, accurate judgments can be made based on the same set of associated data, exhibiting strong scenario robustness. Additionally, by integrating preset cooked temperature values ​​and residual heat (preferably also considering the steady-state duration of temperature), the cookedness and taste stability of fresh grilled meat are guaranteed.

[0150] It should be specifically noted that the flowchart representations of the embodiments described above in this disclosure can be understood as representing a module, segment, or portion of code comprising one or more executable instructions configured to implement a specific logical function or process. Furthermore, the scope of the preferred embodiments of this disclosure includes other implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved.

[0151] For example, Figure 8 The order of the steps in the method embodiment may vary in specific scenarios and is not limited to the above representation.

[0152] This disclosure embodiment may also provide a computer-readable storage medium storing a computer program or instructions, which are executed by the embedded processor 150 before being implemented. Figure 8 The method flow or function in the embodiments.

[0153] That is, the method steps in the above embodiments are implemented as software or computer code that can be stored in a recording medium (such as CD ROM, RAM, floppy disk, hard disk or magneto-optical disk), or implemented as computer code that is originally stored in a remote recording medium or a non-transitory machine-readable medium and will be stored in a local recording medium after being downloaded via a network, so that the method represented herein can be stored in such software processing on a recording medium using a general-purpose computer, a special processor or programmable or special hardware (such as ASIC or FPGA).

[0154] This disclosure may also provide a computer program product, in which one or more computer programs or instructions are run to perform all or part of the processes or functions described in this disclosure, for example... Figure 8The process steps in the method embodiments. The computer program product includes one or more computer programs or instructions.

[0155] Computer programs or instructions can be stored in a readable storage medium or transferred from one readable storage medium to another. For example, the computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The readable storage medium can be any available medium capable of access, or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; an optical medium, such as a digital video optical disc; or a semiconductor medium, such as a solid-state drive. The computer-readable storage medium can be a volatile or non-volatile storage medium, or it can include both volatile and non-volatile types of storage media.

[0156] In some embodiments, this disclosure may also provide a thermometer, including the temperature measuring device 100 described in any of the previous embodiments. As an example, the thermometer may include a wireless circuit (such as Bluetooth) communicatively connected to an embedded processor 150, wirelessly transmitting the measured temperature signal value for display, such as on the display screen of an oven or a mobile terminal (such as a smartphone with a corresponding app). As an example, the thermometer may be implemented as a probe inserted into the oven, or it may be implemented as a temperature measuring probe inserted into the food being baked.

[0157] In some embodiments, this disclosure may also provide a baking appliance that includes the temperature measuring device 100 described in any of the previous embodiments. Alternatively, it may include the thermometer described in the previous embodiments, and does not limit the implementation of the integrated temperature measuring device 100 in the baking appliance.

[0158] In summary, this disclosure relates to the field of temperature measurement technology, providing a temperature measuring device, thermometer, and baking oven for use in baking. The device includes: a K-type thermocouple element; a pre-processing circuit; an analog-to-digital conversion circuit to convert the pre-processed thermocouple signal into a temperature measurement digital signal; an ambient temperature sensor to collect the cold junction temperature signal of the thermocouple element; an embedded processor to obtain a temperature measurement digital sample value and a cold junction signal sample value based on the temperature measurement digital signal and the cold junction temperature signal, respectively; determining the sign direction of the temperature measurement value based on the temperature measurement digital sample value; determining the cold junction compensation calculation method based on the sign direction; calculating the compensated temperature measurement signal value according to the cold junction compensation calculation method using the temperature measurement signal value converted from the sample value and the cold junction temperature signal value, converting the compensated temperature measurement value, and filtering it to obtain the target temperature measurement value. The use of a high-temperature resistant K-type thermocouple solves the problem of high-temperature damage and failure of the temperature probe, and, combined with automated cold junction compensation and filtering, obtains accurate temperature measurement results. In addition, this disclosure can also provide a temperature measuring device with a baking food removal prompt function, which can detect the temperature of the baked food and prompt it to be removed from the oven when it is at the appropriate doneness. This can help users, especially those with less baking experience, to easily bake baked food that is properly cooked and tastes delicious, effectively improving the user experience.

[0159] The above embodiments are merely illustrative of the principles and effects of this disclosure and are not intended to limit this disclosure. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this disclosure. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this disclosure should still be covered by the protection scope of this disclosure.

Claims

1. A temperature measuring device for baking utensils, characterized in that, include: Type K thermocouple elements are used to collect thermocouple signals; The preprocessing circuit is electrically connected to the thermocouple element and is used to receive thermocouple signals and perform preprocessing. An analog-to-digital converter circuit, connected to the stage following the preprocessing circuit, is used to convert the preprocessed thermocouple signal into a temperature measurement digital signal; wherein, the analog-to-digital converter circuit allows data output in two's complement format; An ambient temperature sensor is used to collect ambient temperature signals as the cold junction temperature signal of a thermocouple element. An embedded processor, connected to the analog-to-digital converter circuit and the ambient temperature sensor, is used to receive the temperature measurement digital signal and the cold junction temperature signal, and obtain the temperature measurement digital sample value and the cold junction temperature value respectively; based on the comparison between the temperature measurement digital sample value and at least one range boundary threshold in the sampling range of the analog-to-digital converter circuit / or the disconnection event of the thermocouple element, it determines the sign direction of the temperature measurement value corresponding to the temperature measurement digital sample value and / or the disconnection event of the thermocouple element; according to the sign direction, it determines the cold junction compensation calculation method corresponding to the temperature measurement signal value and the cold junction temperature signal value, wherein the temperature measurement signal value and the cold junction temperature signal value are respectively converted from the temperature measurement digital sample value and the cold junction temperature value; it calculates the compensated temperature signal value after the temperature measurement signal value is compensated by the cold junction temperature signal value through the cold junction compensation calculation method; and it obtains the target temperature measurement value by filtering the compensated temperature measurement value converted from the compensated temperature signal value.

2. The temperature measuring device according to claim 1, characterized in that, The filtering process includes: Obtain the current compensated temperature measurement value and the historical compensated temperature measurement value, and perform smoothing filtering to obtain the smoothed filtered value of the current compensated temperature measurement value; The difference between the current compensated temperature measurement value and the smoothed filter value is compared to obtain the noise value; Determine whether the noise value is greater than a preset threshold; The observation noise covariance is increased or decreased according to whether the noise value is greater than or less than a preset threshold; wherein, the observation noise covariance is used in a Kalman filter; The current compensated temperature value is filtered by the Kalman filter based on the observation noise covariance to obtain the current target temperature value.

3. The temperature measuring device according to claim 1, characterized in that, The preprocessing circuit includes: a thermocouple interface, which is electrically connected to the thermocouple element to receive thermocouple signals, and a signal line, wherein the signal line includes a positive signal line and a negative signal line; The analog-to-digital conversion circuit is connected to the stage after the preprocessing circuit in the signal line, and is used to convert the preprocessed thermocouple signal into a temperature measurement digital signal. The analog-to-digital conversion circuit includes: a differential input interface, including a differential positive input terminal connected to the positive signal line and a differential negative input terminal connected to the negative signal line; and an output interface, including a temperature measurement digital signal obtained by analog-to-digital conversion based on the differential voltage value between the differential positive input terminal and the differential negative input terminal, so as to obtain a measured temperature signal value based on the temperature measurement digital signal.

4. The temperature measuring device according to claim 3, characterized in that, The preprocessing circuit further includes a disconnection detection circuit, which, in response to detecting that the signal line is disconnected from the thermocouple element, changes the voltage on the differential positive input terminal and / or differential negative input terminal so that the differential voltage value is at the disconnection voltage value indicating the disconnection.

5. The temperature measuring device according to claim 4, characterized in that, The disconnection detection circuit includes: The first reference voltage unit includes: a resistor voltage divider circuit connected between the first voltage source and ground, wherein the voltage divider point is connected to the first connection point in the positive signal line to set the first reference voltage; The second reference voltage unit includes: a resistor, one end of which is connected to a second connection point symmetrical to the first connection point on the negative signal line, and the other end of which is connected to a reference terminal having a second reference voltage.

6. The temperature measuring device according to claim 1 or 4, characterized in that, The analog-to-digital conversion circuit includes a power supply terminal, a ground terminal, and a conversion reference input terminal; the power supply terminal is connected to a voltage source, the ground terminal is grounded, and the conversion reference input terminal is connected to a decoupling filter circuit, which includes an RC filter or a capacitor filter circuit.

7. The temperature measuring device according to claim 4, characterized in that, The preprocessing circuit further includes: An electrostatic protection unit is connected between the thermocouple interface and ground. An input impedance matching unit, connected to the electrostatic protection unit, is used to match the input impedance of the thermocouple element; The filtering unit is connected to the input impedance matching unit and the analog-to-digital conversion circuit. The connection point between the disconnection detection circuit and the signal line is located after the electrostatic protection unit and before the input impedance matching unit.

8. The temperature measuring device according to claim 1, characterized in that, The K-type thermocouple element is configured in a temperature probe end for probing into the food being baked; The temperature measuring device also includes: Interactive components allow users to set baking mode information, including the type of food to be baked and the type of baking utensils. The memory is used to store: first associated data for each type of baked item and its associated preset cooking temperature value; second associated data for each type of baking utensil and its associated residual heat correction coefficient; and third associated data between multiple sets of preset conditions constructed based on the average temperature rise rate and the temperature rise rate fluctuation range, and associated temperature measurement condition information and basic residual heat value; the temperature measurement condition information includes the probe's insertion state information in the baked item, and the thickness level information of the baked item when the probe is in place. The embedded processor, coupled to the interactive component and the memory, is used to perform the following: determining the current type of food to be baked and the current type of baking utensils based on the baking mode information selected by the user; calculating the average temperature rise rate and the temperature rise rate fluctuation range based on the target temperature measurement data obtained over a period of time, and matching the probe insertion status information in the third associated data according to the average temperature rise rate and the temperature rise rate fluctuation range; in response to determining that the probe end is in place in the current food to be baked according to the probe insertion status information, obtaining the thickness level information and basic residual heat value of the current food to be baked in the third associated data; determining the residual heat correction coefficient in the second associated data based on the current type of baking utensils, and correcting the basic residual heat value according to the residual heat correction coefficient to obtain a corrected residual heat value; subtracting the corrected residual heat value from the preset cooking temperature value associated in the first associated data according to the current type of food to obtain the target cooking temperature value, and outputting a prompt signal when the target temperature measurement value meets the conditions for removing the food from the oven including the target cooking temperature value.

9. A thermometer, characterized in that, Includes the temperature measuring device as described in any one of claims 1 to 8.

10. A baking appliance, characterized in that, include: The temperature measuring device as described in any one of claims 1 to 8; Alternatively, the thermometer as described in claim 9.

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