Sensing and control apparatus and method for a weight measuring device

Abstract

The invention relates to a sensing and control device (40) and method for a weight measuring device (30) comprising a loading unit for loading material to be weighed. In order to be able to measure accurately with less expensive components, the sensing and control device comprises an analog circuit (50) and a control circuit (60). The analog circuit (50) is configured to receive a weight measuring signal, to convert the received weight measuring signal into a first voltage signal, to subtract a second voltage signal from the first voltage signal when the loading unit is loaded with material to be weighed to generate a third voltage signal representing the weight of the material to be weighed, the second voltage signal representing the weight of at least the loading unit not loaded with material to be weighed. The control circuit (60) is configured to receive the first voltage signal when the loading unit is not loaded with material to be weighed, to convert the first voltage signal into a first digital signal, and to generate a pulse width modulation, PWM, signal having a pulse width, the pulse width representing the weight measured by the weight measuring device when the loading unit is not loaded with material to be weighed, and the control circuit is further configured to convert the third voltage signal into a second digital signal representing a weight measurement of the material to be weighed. The analog circuit (50) is configured to generate the second voltage signal from the PWM signal generated by the control circuit, wherein the voltage level of the second voltage signal is proportional to the pulse width of the PWM signal.

Description

Technical Field

[0001] This invention relates to a sensing and control device and method for a weight measuring apparatus, the weight measuring apparatus including a loading unit for loading material to be weighed. The invention also relates to weight measuring apparatus and cooking apparatus. Background Technology

[0002] Today, a trend in home kitchen appliances is to automate the cooking process, freeing consumers from long waits, interruptions, and failed results. Monitoring the weight changes of food during cooking has proven to be a good indicator of its doneness in many dry cooking methods, such as baking, roasting, stir-frying, and deep-frying. This is typically achieved by converting gravity into an electrical signal using a load cell (or more generally, a weight measuring device comprising a loading unit loaded with the material to be weighed), amplifying the signal to match the range of an analog-to-digital converter (ADC), quantizing it into digital data by the ADC, and feeding it to a control unit (e.g., a microcontroller unit, MCU) for calculation.

[0003] EP2540199A1 discloses an electric heating cooker with weighing function and the weighing control method provided therein. An electronic scale with weighing function is added to a traditional electric heating cooker, and the scale stores a cooking experience database and a food information database. It solves the problem of inaccurate water addition for a given weight of ingredients. Furthermore, it designs empirical curves for heating power at different weight points for foods such as rice and meat, allowing the cooker to intelligently adjust parameters based on user taste feedback, thus better catering to the user's preferences in future cooking. In addition, it can display the total and average content of calories, cholesterol, protein, fat, salt, and cooking oil in the current cooking process or for various foods.

[0004] In practice, it's difficult to configure a fulcrum device to directly weigh food. Instead, it's common to configure the cooking container or even the entire cooking appliance, including the food, for direct weighing. Meanwhile, high-end devices, by integrating multiple cooking functions (e.g., microwave, steam, radiation, convection heating, and stirring), using more powerful components, and having larger volumes, are able to process more food faster and with better results. This trend makes these devices significantly heavier than previous devices and the food being cooked itself. To accurately measure changes in food weight, it's necessary to reduce the load on the fulcrum device other than the food, or to use a high-precision ADC with a wider dynamic range to cover both the load unit quantity (or even the entire weight measuring device) and the total weight of the food. Reducing the load requires complex mechanical isolation or placing the fulcrum closer to the food and harsh cooking environments, which can affect sensing accuracy. The use of high-precision ADCs with a wider dynamic range is truly widespread due to their simplicity, but at the same time, expensive ADCs are increasingly wasted on the increased weight of today's devices.

[0005] Therefore, there is a need for a solution that quantifies only the effective portion of the load (i.e., the material to be weighed loaded in the loading unit), and in particular, a solution that can measure the weight change of food during cooking, so that even a low-cost ADC (which can typically be integrated as a unit of an MCU but with a low bit depth) can meet the range and accuracy required for monitoring the cooking status of food. Summary of the Invention

[0006] The object of this invention is to provide a sensing and control device and method for a weight measuring apparatus. The apparatus includes a loading unit for loading material to be weighed, which can use a low-cost ADC (Analog-to-Digital Converter) while still accurately measuring the material, such as food in an automated cooking process. This invention also relates to corresponding weight measuring devices and corresponding cooking devices.

[0007] A first aspect of the present invention provides a sensing and control device, comprising:

[0008] - An analog circuit is configured to: receive a weight measurement signal; convert the received weight measurement signal into a first voltage signal; subtract a second voltage signal from the first voltage signal when the loading unit is loaded with material to be weighed, to generate a third voltage signal representing the weight of the material to be weighed, wherein the second voltage signal represents at least the weight of the loading unit when it is not loaded with material to be weighed, and

[0009] A control circuit is configured to: receive the first voltage signal when the loading unit is not loaded with material to be weighed; convert the first voltage signal into a first digital signal; and generate a pulse width modulation (PWM) signal having a pulse width representing the weight measured by the weight measuring device when the loading unit is not loaded with material to be weighed. The control circuit is further configured to convert the third voltage signal into a second digital signal representing the weight measurement of the material to be weighed.

[0010] The analog circuit is configured to generate a second voltage signal from the PWM signal generated by the control circuit, wherein the voltage level of the second voltage signal is proportional to the pulse width of the PWM signal.

[0011] Another aspect of the present invention provides a weight measuring device, comprising:

[0012] - Loading unit, configured to load materials to be weighed;

[0013] - A measuring unit is mounted and configured to measure the weight of the material and provide a weight measurement signal; and

[0014] - The sensing and control device disclosed herein is configured to generate a digital signal representing a weight measurement of the material to be weighed, based on the weight measurement signal.

[0015] Another aspect of the present invention provides a cooking apparatus comprising:

[0016] - The weight measuring device disclosed herein; and

[0017] - A heating unit configured to heat the food held in the loading unit of the weight measuring device.

[0018] Another aspect of the present invention provides a sensing and control method for a weight measuring device, the weight measuring device including a loading unit for loading material to be weighed, the sensing and control method comprising:

[0019] - Receive weight measurement signal,

[0020] - Convert the received weight measurement signal into a first voltage signal.

[0021] - The first voltage signal when the loading unit is not loaded with material to be weighed will be converted into a first digital signal.

[0022] - Generate a pulse width modulation (PWM) signal with a pulse width representing the weight measured by the weight measuring device when the loading unit is not loaded with material to be weighed.

[0023] - A second voltage signal is generated from the PWM signal generated by the control circuit, wherein the voltage level of the second voltage signal is proportional to the pulse width of the PWM signal.

[0024] - Subtract the second voltage signal from the first voltage signal when the loading unit is loaded with material to be weighed to generate a third voltage signal representing the weight of the material to be weighed, wherein the second voltage signal represents the weight of the loading unit when it is not loaded with material to be weighed.

[0025] - Convert the third voltage signal (optionally, after amplification) into a second digital signal representing the weight measurement of the material to be weighed.

[0026] Another aspect of the invention provides a corresponding sensing and control method, a computer program comprising program code methods. When the computer program is executed on a computer, the program code methods are used to cause the computer to perform the steps of the method disclosed in this patent, and a non-transitory computer-readable recording medium storing the computer program product. When the computer program product is executed by a processor, the method disclosed in this patent will be performed.

[0027] Preferred embodiments of the invention are defined in the dependent claims. It should be understood that the claimed methods, systems, computer programs, and media have preferred embodiments similar to and / or identical to the claimed sensing and control devices, particularly those as defined in the dependent claims and disclosed in this patent.

[0028] This invention proposes a low-cost solution for measuring the weight change of materials (e.g., food) during cooking in large and heavy kitchen appliances, preferably using a functional module typically integrated into an MCU, rather than using other discrete devices. In this solution, the load on the weight measuring device (e.g., primarily the weight of the cooking appliance and its accessories) is recorded before the material to be weighed (e.g., food) is loaded and proportionally converted to a DC level based on an integrated PWM setting. The DC voltage is analogously subtracted from the total weight (i.e., the weight of the material and loading unit in the cooking appliance example measured during cooking). The resulting signal level is (optionally amplified and) fed to an ADC so that the limited effective bits of the integrated ADC can be used only to quantify the weight change of the material, without wasting them on parts that remain constant in the total weight (e.g., the loading unit). Therefore, this invention is more cost-effective for weight monitoring (e.g., in food processing). Generally, this invention can also be applied to weight measuring devices in various applications and fields, such as weight measuring devices in pharmacy, chemistry, and materials science—scenarios where accurate and inexpensive measurements are generally required.

[0029] In one embodiment, the analog circuit includes a low-pass filter configured to filter the PWM signal to generate a second voltage signal. The second voltage is preferably a DC voltage, and therefore a time-averaged rectangular waveform voltage.

[0030] In another embodiment, the analog circuitry includes a PWM driver configured to convert a PWM signal into an optimized PWM signal with a more consistent voltage level and transition, wherein the analog circuitry is configured to generate a second voltage signal from the optimized PWM signal. Therefore, the PWM driver outputs a rectangular waveform voltage and is typically able to modify the amplitude and transition (i.e., edges) of the PWM signal while maintaining the pulse width.

[0031] In another embodiment, the analog circuit includes a first amplifier configured to amplify a first voltage signal and / or a second amplifier configured to amplify a third voltage signal. This allows full utilization of the available sensitivity of subsequent components.

[0032] In another embodiment, the analog circuit includes a subtraction unit configured to subtract a second voltage signal from a first voltage signal. The output of the subtraction unit is a third voltage signal, preferably a DC voltage proportional to the weight of the material to be weighed.

[0033] The analog circuit may further include a differential amplifier configured to receive a DC voltage signal representing the weight measurement signal. For example, the weight measurement signal may be output from the measurement bridge of, for example, a weighing sensor measurement bridge.

[0034] In one embodiment, the control circuit is configured to select a first voltage signal or a third voltage signal for analog-to-digital conversion into a first digital signal and a second digital signal, respectively. Preferably, a multiplexer can be provided for this purpose.

[0035] Preferably, the control circuit includes a memory configured to store a first digital signal, a counter configured to convert the first digital signal into a pulse width of a rectangular waveform, and / or a PWM generator configured to generate a PWM signal. Attached Figure Description

[0036] These and other aspects of the invention will become clear with reference to the embodiments described below. In the following figures:

[0037] Figure 1A A schematic diagram of a conventional cooking device is shown.

[0038] Figure 1B A schematic diagram of a conventional sensing and control device is shown.

[0039] Figure 2 A schematic diagram of a cooking apparatus according to the present invention is shown, the cooking apparatus including a weight measuring device and a sensing and control device according to the present invention.

[0040] Figure 3 A schematic diagram showing more details of an embodiment of the sensing and control device according to the present invention is provided.

[0041] Figure 4 A circuit diagram of an embodiment of a PWM driver is shown.

[0042] Figure 5 The signal diagrams of the input and output signals of the PWM driver are shown, as well as...

[0043] Figure 6 A flowchart of the sensing and control method according to the present invention is shown. Detailed Implementation

[0044] The following description explains the invention with reference to its application in cooking appliances, but the invention is not limited thereto.

[0045] Figure 1A A schematic diagram of a conventional cooking appliance 10 is shown. In a typical embodiment of the weighing function of such a cooking appliance 10, a weight measuring device 11 is arranged at the bottom of the cooking appliance 10, the weight measuring device including a load cell 12 (generally, the load measuring unit includes one or more load measuring elements, such as a load cell or load sensor). The weight measuring device 11 thus measures the entire cooking appliance 10, including cooked food arranged in a loading unit 13, which in this embodiment is a compartment of the cooking appliance 10 to avoid harsh cooking environments. The cooking appliance 10 also includes sensing and control devices 14, which in... Figure 1B The image is shown in more detail. According to this embodiment, the sensing and control device 14 is coupled to the load cell 12 via a measurement bridge 15, and the sensing and control device includes a differential amplifier 16, an amplifier 17, an analog-to-digital converter (ADC) 18, and a control unit (MCU) 19.

[0046] The arrangement of the weight measuring device 11 at the bottom of the heating cooker 10 not only means that the load cell 12, the measuring bridge 15, and the sensing and control device 14 need to cover the entire range of total weight, including most of the "self-weight" that is not related to the sensing purpose (state monitoring and control), but also means that the ADC 18 needs to have a large bit depth to resolve a large number of partitions for the required accuracy, while most of the partitions are wasted at least on the weight of the loading unit 13 or even the entire cooking device 10.

[0047] Taking a 7000g air fryer as an example, to cook a maximum load of 500g of food, an accuracy of 1 gram is required. When measuring and quantifying the total weight, at least 7500 / 1 = 7500 partitions are needed to resolve 1 gram, which requires 13 significant bits (2^18) in the ADC. 13 =8192). In fact, in ADC applications, there are several nonlinear effects that reduce the number of effective bits by at least 1 to 2 bits. Therefore, to achieve 13 effective bits, this can be achieved by upgrading the ADC to a higher-level MCU or by adding discrete ADCs, using a more expensive 14 / 15-bit ADC. However, the change of real interest is 1 gram in the 500-gram range, which only requires 500 partitions or 9(2 9 =512) valid bits, which can be solved by a 12-bit ADC with a safety margin and is usually integrated at a lower level of the MCU.

[0048] This indicates that the large "weight" of the cooking equipment (and its possible accessories) is subtracted from the analog output of the calorimeter as an offset; preferably, only the weight of the "effective" food being cooked is fed back to the ADC, the so-called "analog tare." However, some issues still need to be addressed:

[0049] 1) The weight itself is not absolutely constant, but is affected by the stresses on items such as accessories (baking pan, grill, basket) and power cords, which can be enormous compared to the weight of the food. If only a fixed offset is subtracted analogously, and other semi-active loads must be counted digitally, a range and resolution margin (e.g., an extra bit) also needs to be reserved for cost. To count semi-active but irrelevant loads (which vary with settings but remain stationary during a cooking session), the actual “inactive” load can be measured before the food load at the start of each cooking stage and then subtracted from the analog signal in front of the ADC.

[0050] 2) Ineffective payloads can be stored and subsequently converted into the payload to be subtracted. kind Compare Signal To obtain the "analog effective gross weight," however, unlike analog-to-digital conversion, even inaccurate digital-to-analog conversion is typically not an integrated unit of an MCU and may require costly construction using discrete components. Therefore, this invention provides a solution for "analog effective gross weight" in cooking process weighing, preferably using a commonly integrated unit within an MCU, thereby maximizing the cost efficiency of the cooking equipment.

[0051] Figure 2A schematic diagram of a cooking apparatus 20 according to the present invention is shown, which includes a weight measuring device 30 and a sensing and control device 40 according to the present invention. The cooking apparatus 20 includes the weight measuring device 30 and a heating unit 21 configured to heat food held in a loading unit 31 of the weight measuring device 30. For example, the loading unit 31 may be configured as a separate container or the cooking chamber of the cooking apparatus 20 (in this embodiment, for example, as a food holder).

[0052] The weight measuring device 30 or cooking device includes a loading unit 31 and a loading measuring unit 32. The loading unit 31 is configured to load the material to be weighed, i.e., the food in this embodiment. The loading measuring unit 32 is, for example, a load cell or weighing sensor device configured to measure the weight of the material and provide a weight measurement signal. The loading measuring unit 32 is placed at the bottom or below the cooking device 20 or the vertically separated loading unit 31, such that during cooking, the total weight or a portion of the weight of the cooking device plus the weight of the food will be weighed. The weight measuring device 30 also includes a sensing and control device 40, which is configured to generate a digital signal representing the weight measurement of the material to be weighed based on the weight measurement signal.

[0053] The sensing and control device 40 typically performs steps such as signal readout, processing, conversion and recording, calculation and control. The sensing and control device 40 mainly comprises two parts, referred to as analog circuitry 50 and control circuitry 60.

[0054] The analog circuit 50 is configured to: receive a weight measurement signal; convert the received weight measurement signal into a first voltage signal; subtract a second voltage signal from the first voltage signal to generate a third voltage signal representing the weight of the material to be weighed, wherein the second voltage signal represents the weight of at least the loading unit without the material to be weighed.

[0055] The control circuit 60 is configured to: receive the first voltage signal when the loading unit is not loaded with material to be weighed; convert the first voltage signal into a first digital signal; and generate a pulse width modulation (PWM) signal having a pulse width representing the weight measured by the weight measuring device when the loading unit is not loaded with material to be weighed. The control circuit is also configured to convert the third voltage signal into a second digital signal representing the weight measurement of the material to be weighed.

[0056] The analog circuit 50 is also configured to generate a second voltage signal from the PWM signal generated by the control circuit, wherein the voltage level of the second voltage signal is proportional to the pulse width of the PWM signal.

[0057] Figure 3 A schematic diagram showing further details of an embodiment of the sensing and control device 40 according to the present invention is provided.

[0058] Load cell 32, for example, arrangement of a piezoresistive or piezoelectric device, in the food loading (denoted as W) A ) and maximum food load (denoted as W) F-M Before this, its maximum load rating is greater than the total weight of the gravimetric device (or more likely, the entire cooking appliance 20 including its accessories, but this does not exclude the possibility that only a portion of the cooking appliance is loaded with food and mechanically isolated from the rest of the cooking appliance). The load meter is affected by the weight of the load, causing a proportional change in its resistance or charge.

[0059] The load cell 32 can be connected to a circuit (e.g., for better sensitivity, such as...). Figure 1B In the bridge circuit 15 shown, its output DC voltage signal (typically the differential voltage between the diagonals of the bridge circuit 15, which is then converted into a voltage relative to ground for subsequent processing) is proportional to the change in resistance or capacitance and to the total load gravity.

[0060] The gauge output voltage representing the weight measurement signal S is amplified by a total gain G1, which uses a first amplifier 52 to obtain a first voltage signal V1. Gain G1 may be included in the positive input V fed to the subtraction unit 53. P The gain of the previous differential amplifier 51 (if not uniform, then the amplifier 51 receives the output of bridge circuit 15). The negative input V of subtraction unit 53. N It is fed by a second DC voltage V2. P and V N respectively with W A +W F and W A They are in the same proportion. Therefore, the output V of the subtraction unit 53, representing the third voltage signal V3, is... D With V P and V N The difference between them is proportional, and thus proportional to the weight W of the food. F Proportional.

[0061] In this embodiment, V N Derived from the digital-to-analog converter (DAC) 54, its digital input is for "non-load" (W) A The binary quantization of gravity, "non-payload" (W) AThe food is weighed before loading and stored in memory 63 of control circuit 60. In this embodiment, a high-precision DAC 54 is implemented by low-pass filtering a rectangular waveform to a DC voltage. The duty cycle (or pulse width) of the rectangular waveform is controlled by counter 64 (i.e., pulse width modulation). The count is performed on W loaded from memory 63. A The binary record. The rectangular waveform generator (or PWM generator) 65 is typically integrated into mainstream control circuitry at no additional cost. Alternatively, the DAC 54 can also be an integrated device (e.g., a DAC IC chip), or constructed at a higher cost using discrete components in a cascaded architecture.

[0062] To improve sensitivity to the weight of the target food, V D Before being fed to the analog input of ADC 62, the signal can be further amplified by a second amplifier 55 with a gain G2 (possibly including the gain of the subtraction unit 53, if this is not uniform) according to the reference voltage V of ADC 62. R To (W) F / W F-M )·A·V R Scaling is applied. Here, A is a predetermined fraction of the full range of the ADC 62. Therefore, in an N-bit ADC 62, the maximum food load gravity (W) is... F-M ) will be quantized to A2 in binary form N The actual food load W F It will be quantized in binary form as (W F / W F-M )·A·2 N Thus, the resolution is W F-M / (A·2 N When the effective bit depth NE is less than N, the effective resolution is increased to W. F-M / (A·2 NE ).

[0063] For example, if the integrated 12-bit low-cost ADC 62 only has 10 valid bits, and fully utilizes (A=1) to maximize coverage of a 500g food load (W) F-M If the weight of food is 500g, then the effective resolution is 500 / 1024≈0.5g, which is usually sufficient to monitor the weight of food during cooking.

[0064] Therefore, there are two types with very different weights (W) A With W F W A >>W FThis requires digitization. This can be economically addressed in one embodiment, which features a multiplexer 61 preceding an ADC 62 typically integrated into control circuitry 60. One input of the multiplexer 61 is connected to the output of a first amplifier 52 with gain G1, and another input of the multiplexer 61 is connected to the output of a second amplifier 55 with gain G2, where G1 will scale a relatively large voltage V. P Voltage V P Mainly represents W A To match ADC 62 in A·V R The full scale of W is used, while G2 will scale a relatively small VD signal to maximize the representation of W. F-M To match A·V R The full scale.

[0065] In order for this solution to work properly during the cooking process to monitor food weight, a weight of W is measured before loading the food. A The empty cooking device (including food) is weighed, digitally quantified, and stored in memory 63. At this time, the voltage V... P It should be approximately equal to the voltage V. N , make difference V D As close to zero as possible. The output DC voltage V of the low-pass filter 54. N The voltage is proportional to the time-averaged voltage of the rectangular waveform, which is the duty cycle R and the “ON” amplitude V. On The product of, i.e., V N =R·V On R=T on / T, where T is the repetition period of the rectangular waveform, T on The duration of the "ON" pulse is controlled by a counter number loaded in memory 63, which is W. A The numerical representation.

[0066] Since the "ON" and "OFF" digital voltages output from the control circuit 60 represent digital logic states rather than precise and constant voltage values, a driver circuit 56, such as a PWM driver, can be added before the filter circuit 54. Figure 4 As shown in the embodiment, the driver circuit 56 includes a pair of inexpensive MOSFETs of the same type, whose gate terminals are connected together to the PWM output of the control circuit 60, whose drain terminals are connected together to the input of the filter circuit 54, and whose source terminals are respectively connected to an analog positive power supply V. R It is connected to the earth. Figure 4The circuit shown is an example of a simple two-stage RC low-pass filter, but it is not limited to this form. Therefore, the "ON" voltage of the PWM output will switch the P-type and N-type MOSFETs to short-circuit and open-circuit states respectively, and pull the drain terminals to V. R Conversely, the "OFF" voltage pulls the drain terminal to zero, thus making the voltage values ​​in the PWM more accurate and consistent, such as... Figure 5 The simulation results are shown below. The simulation results show that the filtered PWM(V) N The peak-to-peak oscillation of ) is less than V. R 1 / 2 17 (Assuming the ADC reference voltage is the same), this interference has a non-negligible impact on performance. Figure 5 Specifically shown are the digital PWM output 70 from the control circuit 60, the PWM output 71 from the PWM driver 56, and the filtered DC voltage output 72.

[0067] Therefore, according to the present invention, the first voltage signal is converted from the received weight measurement signal, and depending on whether material is loaded, the first voltage signal may represent only the weight of the container, or it may represent the weight of the container and the food. Specifically, the first voltage signal may represent the weight of the container when no material is loaded. The first voltage signal when no material is loaded onto the loading unit is specifically used to calculate the second voltage signal. And when material is added to the loading unit, the first voltage signal may also represent the total weight of the container and the food material. In this case, the first voltage can be used when material is added to calculate the third voltage signal.

[0068] Figure 6 A flowchart of a sensing and control method 100 for a weight measuring device according to the present invention is shown. The weight measuring device includes a loading unit for loading material to be weighed. The sensing and control method 100 includes the following steps:

[0069] S1: Receive weight measurement signal.

[0070] S2: Convert the received weight measurement signal into a first voltage signal.

[0071] S3: Converts the first voltage signal when the loading unit is not loaded with material to be weighed into a first digital signal.

[0072] S4: Generate a PWM signal with pulse width modulation, the pulse width of which represents the weight measured by a weight measuring device when the loading unit is not loaded with material to be weighed.

[0073] S5: Generate a second voltage signal from the PWM signal generated by the control circuit, wherein the voltage level of the second voltage signal is proportional to the pulse width of the PWM signal.

[0074] S6: Subtract the second voltage signal from the first voltage signal when the loading unit is loaded with material to be weighed to generate a third voltage signal representing the weight of the material to be weighed, wherein the second voltage signal represents at least the weight of the loading unit when it is not loaded with material to be weighed.

[0075] S7: Convert the third voltage signal into a second digital signal, which represents the weight measurement of the material to be weighed.

[0076] This invention can be applied to any weighing solution, such as for cooking status monitoring, which analogously subtracts a portion or all of the invalid weight of the equipment (e.g., cooking equipment) from the total weight to obtain the weight of the target material (food) (the target material weight is valid during operation, such as cooking), particularly the invalid weight collected before loading the material and encoded with a pulse waveform. This invention is preferably applied to weighing-based or assisted cooking status monitoring in home or commercial kitchen applications.

[0077] Although the invention has been illustrated and described in detail in the accompanying drawings and the foregoing description, such illustrations and descriptions should be considered illustrative or exemplary rather than limiting; the invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments can be understood and implemented by those skilled in the art in practicing the claimed invention through study of the drawings, the disclosure, and the appended claims.

[0078] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. A single element or other unit can perform the functions of several items recited in the claims. The fact that certain measures are recited in different dependent claims does not mean that combinations of these measures cannot be used advantageously.

[0079] Computer programs may be stored / distributed on suitable non-transitory media, such as optical storage media or solid-state media provided together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0080] No reference numerals in the claims should be construed as limiting the scope.

Claims

1. A sensing and control device for a gravimetric measuring device, comprising a loading unit for loading material to be weighed, characterized in that, The sensing and control device comprises - an analog circuit (50) configured to receive a weight measurement signal from a load measurement unit (32), to convert the received weight measurement signal into a first voltage signal, to subtract a second voltage signal from the first voltage signal when the load cell is loaded with material to be weighed, to generate a third voltage signal representing the weight of the material to be weighed, the second voltage signal representing the weight of at least the load cell not loaded with material to be weighed, wherein the analog circuit (50) comprises a first amplifier (52) configured to amplify the first voltage signal, and a second amplifier (55) configured to amplify the third voltage signal, and - A control circuit (60) is configured to: receive a first voltage signal from the analog circuit (50) when the loading unit is not loaded with material to be weighed; convert the first voltage signal into a first digital signal; and generate a pulse width modulation (PWM) signal having a pulse width representing the weight measured by the weight measuring device when the loading unit is not loaded with material to be weighed, and the control circuit is further configured to convert the third voltage signal into a second digital signal representing the weight measurement of the material to be weighed, wherein the control circuit (60) includes an analog-to-digital converter (62) and a multiplexer (61) located before the analog-to-digital converter, one input of the multiplexer being connected to the output of the first amplifier with gain G1, and the other input of the multiplexer being connected to the output of the second amplifier with gain G2, wherein G1 is based on the weight W of the unloaded material in the loading unit. A And the full scale of the analog-to-digital converter (62), G2 is based on the weight W of the material to be weighed. F The maximum weight W of the material to be weighed F-M And the full scale of the analog-to-digital converter (62), - wherein the analog circuit (50) is configured to generate the second voltage signal from the PWM signal generated by the control circuit, wherein the voltage level of the second voltage signal is proportional to the pulse width of the PWM signal.

2. The sensing and control device according to claim 1, wherein the analog circuit (50) comprises a low pass filter (54) configured to filter the PWM signal to generate the second voltage signal.

3. The sensing and control device according to claim 1 or 2, wherein the analog circuit (50) comprises a PWM driver (56) configured to convert the PWM signal into an optimized PWM signal having more consistent voltage levels and transitions, wherein the analog circuit is configured to generate the second voltage signal from the optimized PMW signal.

4. The sensing and control device according to any of the preceding claims 1 to 2, wherein the analog circuit (50) comprises a subtraction unit (53) configured to subtract the second voltage signal from the first voltage signal.

5. The sensing and control device according to any of the preceding claims 1 to 2, wherein the analog circuit (50) comprises a differential amplifier (51) configured to receive a DC voltage signal representing the weight measurement signal.

6. The sensing and control device according to any of the preceding claims 1 to 2, wherein the control circuit (60) is configured to select the first voltage signal or the third voltage signal for analog-to-digital conversion into the first digital signal and the second digital signal, respectively.

7. The sensing and control device according to any of the preceding claims 1 to 2, wherein the multiplexer (61) is configured to select the first voltage signal or the third voltage signal for analog-to-digital conversion into the first digital signal and the second digital signal, respectively.

8. The sensing and control device according to any of the preceding claims 1 to 2, wherein the control circuit (60) comprises a memory (63) configured to store the first digital signal.

9. The sensing and control device according to any of the preceding claims 1 to 2, wherein the control circuit (60) comprises a counter (64) configured to convert the first digital signal into a pulse width of a rectangular waveform, and / or a PWM generator (65) configured to generate the PWM signal.

10. A weight measuring device comprising: - a loading unit (31) configured to load material to be weighed; - a load measuring unit (32) configured to measure a weight of the material and to provide a weight measurement signal; and - a sensing and control device (40) according to any one of the preceding claims configured to generate a digital signal representing a weight measurement of the material to be weighed based on the weight measurement signal.

11. A cooking device comprising - a weight measuring device (30) according to claim 10; and - a heating unit (21) configured to heat food held in the loading unit of the weight measuring device.

12. A sensing and control method for a gravimetric measuring apparatus comprising a loading unit for loading material to be weighed and a sensing and control apparatus (40) according to any one of the preceding claims 1 to 9, characterized in that, The sensing and control method comprises: - receiving a weight measurement signal from a weight measuring device, - converting the received weight measurement signal into a first voltage signal, - converting the first voltage signal into a first digital signal when the loading unit is not loaded with material to be weighed, - generating a pulse width modulation, PWM, signal having a pulse width representing the weight measured by the weight measuring device when the loading unit is not loaded with material to be weighed, - generating a second voltage signal from the PWM signal generated by the control circuit, wherein a voltage level of the second voltage signal is proportional to the pulse width of the PWM signal, - subtracting the second voltage signal from the first voltage signal when the loading unit is loaded with material to be weighed to generate a third voltage signal representing the weight of the material to be weighed, the second voltage signal representing at least the weight of the loading unit not loaded with material to be weighed, and - converting the third voltage signal into a second digital signal representing the weight measurement of the material to be weighed.

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