Liquid level detection circuit board, calibration method and system thereof, liquid level detection method and liquid household appliance

Abstract

The application provides a liquid level detection circuit board and a calibration method and system thereof, a liquid level detection method and a household appliance with liquid, which receives a reference signal output by a calibration device, detects the reference signal to obtain a first measurement frequency, acquires an actual frequency of the reference signal, determines a calibration coefficient of the liquid level detection circuit board based on the actual frequency and the first measurement frequency, and compensates the frequency of a liquid level detection circuit output signal obtained by measurement by using the calibration coefficient in a subsequent liquid level detection process, so that the frequency detection error caused by the internal clock deviation of different control devices is reduced by a software calibration mode, an external crystal oscillator does not need to be additionally arranged, and the calibration cost is reduced.

Description

Technical Field

[0001] This application relates to the field of liquid level detection technology, and in particular to a liquid level detection circuit board and its calibration method, system, liquid level detection method, and liquid-using household appliances. Background Technology

[0002] In liquid-using appliances (such as washing machines, dishwashers, coffee machines, and water purifiers), liquid level detection is one of the key technologies for achieving automated control. Taking washing machines as an example, accurate water level detection not only directly affects the washing effect and user experience, but also relates to water resource utilization efficiency, energy consumption control, and the safe operation of the equipment.

[0003] Currently, most liquid-using appliances employ frequency-based liquid level measurement solutions. The working principle is as follows: a liquid level sensor outputs electrical signals of different frequencies based on changes in liquid level. The control chip uses its internal clock to measure the frequency of this signal, and determines the actual liquid level by establishing the correlation between frequency and liquid level. In this technical solution, the accuracy of liquid level detection largely depends on the frequency precision and long-term stability of the control chip's internal clock.

[0004] However, in actual production and application, due to various factors such as manufacturing process deviations, component parameter dispersion, and operating temperature drift, the actual frequency of the internal clock of control chips from different batches, different models, and even the same batch often varies to some extent. This clock frequency deviation causes different control chips to measure different frequency values ​​when the same liquid level sensor outputs the same frequency signal, resulting in a systematic deviation in the liquid level detection results and affecting the consistency and reliability of the product.

[0005] To address the aforementioned issues, traditional techniques typically employ adding an external high-precision crystal oscillator to the printed circuit board. This external clock is used to replace the internal clock for frequency measurement, thereby improving detection accuracy. However, this hardware calibration solution requires modifications to the original circuit design and the addition of materials such as the crystal oscillator, leading to increased costs. Summary of the Invention

[0006] This application provides a liquid level detection circuit board and its calibration method, system, liquid level detection method, and liquid-using household appliances. The software calibration method reduces frequency detection errors caused by internal clock deviations of different control devices, and eliminates the need for an external crystal oscillator, thus reducing calibration costs.

[0007] In a first aspect, embodiments of this application provide a calibration method for a liquid level detection circuit board, comprising: receiving a reference signal output by a calibration device; detecting the reference signal to obtain a first measurement frequency; acquiring the actual frequency of the reference signal; and determining a calibration coefficient for the liquid level detection circuit board based on the actual frequency and the first measurement frequency.

[0008] In one or more embodiments, determining the calibration coefficient of the liquid level detection circuit board based on the actual frequency and the first measurement frequency includes: calculating a first ratio between the first measurement frequency and the actual frequency; and using the first ratio as the calibration coefficient.

[0009] In one or more embodiments, the calibration method further includes storing the calibration coefficients.

[0010] Secondly, embodiments of this application provide a liquid level detection method applied to a control device. The control device is disposed on a liquid level detection circuit board, which further includes a liquid level detection circuit. The liquid level detection circuit board is disposed on a liquid-using appliance. The liquid level detection method includes: obtaining a calibration coefficient of the liquid level detection circuit board based on a calibration method as described in any embodiment of the first aspect; receiving a frequency signal output by the liquid level detection circuit; detecting the frequency signal to obtain a second measurement frequency; calibrating the second measurement frequency based on the calibration coefficient to obtain a third measurement frequency; and determining the liquid level of the liquid-using appliance based on the third measurement frequency.

[0011] In one or more embodiments, calibrating the second measurement frequency based on the calibration coefficient to obtain the third measurement frequency includes: calculating a second ratio between the second measurement frequency and the calibration coefficient; and using the second ratio as the third measurement frequency.

[0012] Thirdly, embodiments of this application provide a control device, including: a processor, and a memory communicatively connected to the processor; the memory stores computer program instructions executable by the processor, which, when executed by the processor, cause the control device to perform the method described in any one of the embodiments of the first and second aspects.

[0013] Fourthly, embodiments of this application provide a liquid level detection circuit board, including a substrate, a liquid level detection circuit, and a control device as described in the third aspect; the liquid level detection circuit is electrically connected to the control device, and the liquid level detection circuit and the control device are disposed on the substrate.

[0014] Fifthly, embodiments of this application provide a liquid-using appliance, including a cavity and a liquid level detection circuit board as described in the fourth aspect; the cavity is configured to contain liquid; and the liquid level detection circuit board is configured to detect the liquid level in the cavity.

[0015] In a sixth aspect, embodiments of this application provide a liquid level calibration system, including a calibration device and a liquid level detection circuit board as described in the fourth aspect; the calibration device is electrically connected to the liquid level detection circuit board; the calibration device is configured to output the reference signal to the liquid level detection circuit board.

[0016] In one or more embodiments, the calibration device includes a signal generation module and a detection module; the signal generation module is electrically connected to the detection module and the liquid level detection circuit board respectively; wherein, the signal generation module is configured to generate the reference signal; in response to the detection module detecting that the actual frequency of the reference signal is equal to a first frequency value, the signal generation module outputs the reference signal to the liquid level detection circuit board; in response to the detection module detecting that the actual frequency of the reference signal is not equal to the first frequency value, the signal generation module does not output the reference signal to the liquid level detection circuit board.

[0017] In a seventh aspect, embodiments of this application also provide a computer storage medium, characterized in that the computer storage medium stores instructions or programs that, when executed by at least one processor, cause the at least one processor to perform the method as described in any one of the embodiments of the first and second aspects.

[0018] Eighthly, embodiments of this application also provide a computer program product, the computer program product including a computer program stored on a computer-readable storage medium, the computer program including program instructions, which, when executed by a computer, cause the computer to perform the methods described in the first and second aspects above.

[0019] The beneficial effects of this application are as follows: This application provides a liquid level detection circuit board and its calibration method, system, liquid level detection method, and liquid-using household appliance. The method involves receiving a reference signal output by a calibration device; detecting the reference signal to obtain a first measurement frequency; obtaining the actual frequency of the reference signal; and determining the calibration coefficient of the liquid level detection circuit board based on the actual frequency and the first measurement frequency. In the subsequent liquid level detection process, the calibration coefficient is used to calibrate and compensate the frequency of the measured liquid level detection circuit output signal. The frequency detection error caused by the internal clock deviation of different control devices is reduced by software calibration, eliminating the need for an external crystal oscillator and reducing calibration costs. Attached Figure Description

[0020] One or more embodiments are illustrated by way of example with reference to the accompanying drawings, and these illustrative descriptions do not constitute a limitation on the embodiments.

[0021] Figure 1 An exemplary structural block diagram of a liquid-cooled household appliance is shown; Figure 2An exemplary structural diagram of a liquid level detection circuit board is shown; Figure 3 An exemplary flowchart illustrates a calibration method for a liquid level detection circuit board; Figure 4 An exemplary flowchart of a liquid level detection method is shown; Figure 5 An exemplary block diagram of a control device is shown; Figure 6 An exemplary block diagram of a calibration system is shown. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Furthermore, the technical features involved in the various embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0024] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0025] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a liquid-cooled household appliance 100 provided in an embodiment of this application. Figure 1 As shown, the liquid appliance 100 includes a cavity 10 and a liquid level detection circuit board 20. The cavity 10 is configured to contain liquid; the liquid level detection circuit board 20 is configured to detect the liquid level inside the cavity 10.

[0026] Liquid-using appliances 100 refer to household appliances that require the use of liquids (such as water or mixtures containing water) during operation. Specifically, liquid-using appliances 100 can include various types of appliances such as washing machines, dishwashers, coffee makers, humidifiers, garment steamers, electric kettles, water purifiers, and water dispensers. The cavity 10 refers to the spatial structure within the liquid-using appliance 100 used to contain the liquid. For example, in a washing machine, the cavity 10 can be the inner tub; in a coffee maker, it can be the water tank. The cavity 10 is typically made of corrosion-resistant and high-temperature-resistant materials, such as stainless steel, engineering plastics (such as ABS, PP, etc.), or other materials suitable for contact with water. The liquid level refers to the height or volume of the liquid within the cavity 10.

[0027] Liquid level detection plays a crucial role in the operation of liquid-using appliances. Accurate liquid level detection ensures that appliances correctly execute their workflow according to preset programs. For example, in washing machines, liquid level detection can control the water intake, ensuring that the appropriate amount of water is added based on the amount of laundry, thus saving water while maintaining washing effectiveness. In coffee machines, liquid level detection can remind users to add water in time, preventing damage to the equipment caused by the heating element burning dry due to lack of water.

[0028] See Figure 2 The liquid level detection circuit board 20 includes a substrate 21, a liquid level detection circuit 22, and a control device 23. The liquid level detection circuit 22 is electrically connected to the control device 23, and both the liquid level detection circuit 22 and the control device 23 are mounted on the substrate 21. The liquid level detection circuit board 20 is a printed circuit board (PCB). The substrate 21 is the supporting carrier of the liquid level detection circuit board 20, usually made of insulating material, providing physical support and electrical connection paths for the electronic components on the liquid level detection circuit board 20. The liquid level detection circuit 22 is a circuit device used to detect the liquid level, including a liquid level sensor, such as a water level sensor. The frequency of the frequency signal output by the liquid level detection circuit 22 has a one-to-one correspondence with the liquid level of the liquid appliance 100. Specifically, as the liquid level in the cavity 10 rises, the frequency of the frequency signal output by the liquid level detection circuit 22 will increase or decrease accordingly (the specific increase or decrease depends on the circuit design). This correspondence can be linear or non-linear, and a mapping table or fitting formula between the frequency and the liquid level can be established through pre-calibration. The specific circuit structure of the liquid level detection circuit 22 can be referred to the existing technology, and is not limited here.

[0029] The control device 23 refers to any combination of components including a microcontroller unit (MCU), a general-purpose processor, a digital signal processor (DSP), a single-chip microcomputer, or the like. The control device 23 can receive a frequency signal output from the liquid level detection circuit 22 via an input interface. This frequency signal can be a square wave or other periodic signal. The control device 23 can use an internal timer to measure the frequency signal, obtain its frequency value, and then determine the current liquid level based on the one-to-one correspondence between the frequency and the liquid level. The specific method by which the control device 23 measures the frequency can be found in existing technologies and is not limited here.

[0030] Due to variations in chip manufacturing processes and operating temperatures, the clock precision of different control devices 23 differs, leading to deviations in the frequency values ​​measured for the same frequency signal. This measurement difference ultimately translates into significant differences in liquid level height, causing inconsistencies in the displayed values ​​or actions performed by different products of the same model under the same liquid level conditions. This results in inconsistent product performance, potentially causing problems such as excessive water intake (leading to overflow, detergent waste, and prolonged washing time) or insufficient water intake (leading to poor washing results, clothing wear and tear, and excessive motor load). Users will clearly perceive the differences between products, impacting brand reputation. Furthermore, inaccurate liquid level detection can lead to product performance issues, resulting in customer complaints and, in severe cases, returns, increasing after-sales costs and market risks for the company.

[0031] Therefore, this application also provides a liquid level detection circuit board and its calibration method, system, liquid level detection method, liquid-using household appliance, control device, and storage medium. The method compensates for the internal clock frequency deviation of the control device 23 through software calibration. During the production or testing phase of the liquid level detection circuit board 20, the calibration device 200 outputs a reference signal with a known actual frequency to the control device 23. The control device 23 uses its internal clock to measure the reference signal to obtain a first measurement frequency, and then calculates the ratio between the first measurement frequency and the actual frequency as a calibration coefficient. In subsequent liquid level detection processes, the control device 23 calibrates and compensates for the frequency of the output signal of the measured liquid level detection circuit 22, thereby reducing systematic measurement errors caused by the chip's own clock deviation. This application eliminates the need to add an external high-precision crystal oscillator and its peripheral components to the printed circuit board, reducing hardware costs, saving PCB space, and offering strong operability. It provides greater flexibility for product miniaturization design, reduces potential failure points, and improves system reliability and environmental adaptability. Meanwhile, this solution requires no modification to the existing hardware circuit design and can be deployed directly through firmware upgrades. It does not require changes to existing production line configurations or processes, making it easy to quickly deploy and apply across existing product lines. It supports online calibration and remote upgrades, shortening product development cycles and improving production efficiency. Furthermore, by precisely calibrating the internal clock frequency of the control device 23, systematic measurement errors caused by clock deviations are reduced, improving liquid level detection accuracy and batch product consistency. This ensures that each product accurately controls the water inflow, improving user experience, reducing product return rates and customer complaint rates, and lowering after-sales maintenance costs.

[0032] The technical solutions provided in this application will be described in detail below with reference to specific embodiments.

[0033] In a first aspect, embodiments of this application provide a calibration method for a liquid level detection circuit board 20, which is applied to the control device 23 provided in this application. (See attached document.) Figure 3 The calibration method includes, but is not limited to, steps S10 to S40.

[0034] Step S10: Receive the reference signal output by the calibration device 200.

[0035] In this step, the control device 23 receives a reference signal from the calibration device 200 through its input interface. The calibration device 200 is a specialized device used during the production, testing, or maintenance of the level detection circuit board 20. It generates a precise, stable, and reliable standard signal as a reference signal. The calibration device 200 typically includes a high-precision signal generator, a communication interface, and other components. The reference signal is a periodic electrical signal with a known frequency and high accuracy, such as a square wave or sine wave. The frequency of the reference signal should be selected within the operating range of the level detection circuit 22's output frequency to ensure the effectiveness of the calibration. For example, if the output frequency range of the level detection circuit 22 is 30Hz to 50Hz, the frequency of the reference signal can be selected near the midpoint of that range, such as 40Hz. The amplitude of the reference signal should match the amplitude of the level detection circuit 22's output signal to ensure that the control device 23 can correctly identify and process it.

[0036] In actual operation, after the liquid level detection circuit board 20 is placed at the test station, the test equipment or operator will start the calibration procedure. The calibration device 200 first performs a self-test to confirm that the internal reference clock is working properly, and then generates a reference signal and outputs it to the liquid level detection circuit board 20. After receiving the reference signal, the control device 23 triggers the corresponding interrupt or event and enters the calibration mode.

[0037] Step S20: Detect the reference signal to obtain the first measurement frequency.

[0038] In this step, the control device 23 uses its internal timer to measure the frequency of the received reference signal to obtain a first measured frequency. The first measured frequency refers to the frequency value of the reference signal measured by the control device 23 based on its internal clock. This frequency value may deviate from the actual frequency of the reference signal, and the magnitude of the deviation depends on the accuracy of the internal clock of the control device 23.

[0039] There are several methods for the control device 23 to measure the frequency, such as the period measurement method or other suitable methods in the prior art. In the period measurement method, the control device 23 measures the period of the reference signal (i.e., the time interval between two adjacent rising or falling edges), and then takes the reciprocal of the period to obtain the frequency.

[0040] To improve measurement accuracy and reliability, in some embodiments, the control device 23 performs multiple detections on the reference signal to obtain a first detection sequence containing multiple detection frequency values. For example, the control device 23 continuously measures the reference signal 10 times to obtain a detection sequence containing 10 frequency values. Then, the control device 23 performs data processing on the detection sequence, such as removing the maximum and minimum values ​​in the first detection sequence to obtain a second detection sequence. Removing the maximum and minimum values ​​can effectively eliminate abnormal values ​​caused by transient interference, measurement jitter, etc. Next, based on the second detection sequence, the first measurement frequency is calculated. The calculation method can be the arithmetic mean, weighted average, or median, etc. Using the arithmetic mean method can effectively reduce random errors and improve the repeatability and stability of the measurement. In some embodiments, during data processing, if the dispersion of each value in the first detection sequence is too large (e.g., the standard deviation exceeds a preset threshold), the control device 23 can determine that the measurement is abnormal, discard the measurement result, and remeasure the reference signal to improve the reliability of the final first measurement frequency.

[0041] Step S30: Obtain the actual frequency of the reference signal.

[0042] The actual frequency refers to the true frequency value of the reference signal, which is precisely controlled and measured by the calibration device 200 and has high accuracy. The actual frequency can be obtained in several ways. In one embodiment, the actual frequency is pre-stored in the memory of the control device 23. For example, before the liquid level detection circuit board 20 leaves the factory or before calibration, the manufacturer or tester writes the actual frequency value of the reference signal into the non-volatile memory (e.g., Flash memory, EEPROM, etc.) of the control device 23 using a programming tool. During calibration, the control device 23 directly reads the actual frequency value from the memory. In another embodiment, the actual frequency is transmitted from the calibration device 200 to the control device 23 via communication. Specifically, while outputting the reference signal, the calibration device 200 sends the actual frequency value in digital form to the control device 23 through a communication interface (e.g., UART, SPI, I2C, USB, etc.). The control device 23 receives and parses this data to obtain the actual frequency value. Compared to the aforementioned methods, this method does not require modification of the firmware of the control device 23 and allows the use of different frequency reference signals in different batches and different test scenarios, improving calibration flexibility.

[0043] Step S40: Determine the calibration coefficient of the liquid level detection circuit board 20 based on the actual frequency and the first measurement frequency.

[0044] In this step, the control device 23 calculates a calibration coefficient based on the actual frequency of the reference signal and the measurement frequency measured by the control device 23. The calibration coefficient is a correction parameter used to compensate for the internal clock frequency deviation of the control device 23. By performing calibration calculations on the measurement frequency in subsequent liquid level detection processes, the systematic error caused by clock frequency deviation can be reduced.

[0045] In this application, the internal clock frequency deviation of the control device 23 is compensated through software calibration. During the production or testing phase of the liquid level detection circuit board 20, a reference signal with a known actual frequency is output to the control device 23 using the calibration device 200. The control device 23 uses its internal clock to measure this reference signal to obtain a first measurement frequency, and then calculates and stores the ratio between the first measurement frequency and the actual frequency as a calibration coefficient. In subsequent liquid level detection processes, the control device 23 calibrates and compensates for the frequency of the output signal of the liquid level detection circuit 22 obtained from the measurement, thereby reducing systematic measurement errors caused by clock frequency deviation. This application eliminates the need to add an external high-precision crystal oscillator and its peripheral components to the printed circuit board, reducing hardware costs, saving PCB space, providing greater flexibility for miniaturized product design, reducing potential failure points, and improving system reliability and environmental adaptability. Furthermore, this solution does not require modification of the original hardware circuit design and can be directly deployed through firmware upgrades without changing the existing production line configuration and process flow. It is easy to quickly promote and apply in existing product series, supports online calibration and remote upgrades, shortens product development cycles, and improves production efficiency. In addition, by precisely calibrating the internal clock frequency of the control device 23, systematic measurement errors caused by clock frequency deviations are reduced, improving the accuracy of liquid level detection and the consistency of batch products. This ensures that each product can accurately control the water intake, improves user experience, reduces product return rates and customer complaint rates, and reduces after-sales maintenance costs.

[0046] In some embodiments, the calibration coefficient of the liquid level detection circuit board 20 is determined based on the actual frequency and the first measurement frequency, including but not limited to steps S41 to S42. Step S41: Calculate a first ratio between the first measurement frequency and the actual frequency. Step S42: Use the first ratio as the calibration coefficient.

[0047] That is, the calibration coefficient is calculated using the following formula: K = F1 / F2; Where K is the calibration coefficient, F1 is the first measurement frequency, and F2 is the actual frequency.

[0048] If F1 is 39.9Hz and F2 is 40Hz, then K = 39.9 / 40 = 0.9975.

[0049] The calibration coefficient reflects the relative deviation of the internal clock frequency of the control device 23. It can be understood that the reciprocal of the calibration coefficient actually represents the ratio between the internal clock frequency of the control device 23 and the frequency of the reference signal.

[0050] In this embodiment, the calibration coefficient can be calculated with only one division operation. The algorithm has low complexity and does not require high processor computing power. It is suitable for low-cost microcontrollers, can quickly complete calibration, and improve production efficiency.

[0051] In some embodiments, the calibration method further includes step S50 of storing calibration coefficients.

[0052] After obtaining the calibration coefficient, the control device 23 stores it in non-volatile memory so that the data can be retained even after power failure for subsequent liquid level detection. The non-volatile memory can be an internal Flash memory, EEPROM, or an external memory chip within the control device 23. When storing the calibration coefficient, in addition to storing the numerical value of the calibration coefficient itself, other calibration-related information can also be stored, such as the calibration date, ambient temperature during calibration, model and serial number of the calibration device 200, the calibration operator's employee number, and verification marks of the calibration results. This additional information helps with product quality traceability and problem analysis.

[0053] To prevent calibration failure due to memory data corruption, in some embodiments, the control device 23 employs a data backup and verification mechanism. For example, the calibration coefficients are stored in two different locations in the memory, each with a CRC checksum. When reading the calibration coefficients, the control device 23 verifies both sets of data. If one set of data is found to be corrupted, the other set is used; if both sets of data are corrupted, the default calibration coefficient (e.g., 1.0) is used, or a calibration failure alarm is triggered.

[0054] After storage is complete, the control device 23 can also send a confirmation signal to the calibration device 200, indicating that the calibration process has been successfully completed. After receiving the confirmation signal, the calibration device 200 can mark the liquid level detection circuit board 20 as having passed calibration in the test record, allowing it to proceed to the next process or be shipped out.

[0055] In some embodiments, to verify the effectiveness of the calibration, after storing the calibration coefficients, the control device 23 can immediately use the calibration coefficients to perform calibration calculations on the measured frequency of the reference signal, obtain the calibrated frequency value, and compare it with the actual frequency. If the deviation between the calibrated frequency value and the actual frequency is within the allowable range, the calibration is considered effective; otherwise, the calibration is considered to have failed and needs to be recalibrated.

[0056] Through the above calibration method, the control device 23 of each liquid level detection circuit board 20 will obtain a personalized calibration coefficient for its internal clock frequency deviation. This calibration coefficient accurately reflects the actual deviation of the clock frequency of the control device 23, laying the foundation for subsequent accurate liquid level detection.

[0057] Secondly, embodiments of this application provide a liquid level detection method, which is applied to the control device 23 provided in this application. (See attached document.) Figure 4 The liquid level detection method includes, but is not limited to, steps S100 to S500.

[0058] Step S100: Based on the calibration method of any embodiment of the first aspect, obtain the calibration coefficient of the liquid level detection circuit board 20.

[0059] In this step, the control device 23 performs the aforementioned calibration method to obtain calibration coefficients. This step is typically performed during the production testing phase of the level detection circuit board 20 or before its first use. In some embodiments, this step may also be performed periodically during the product maintenance phase to compensate for clock frequency drift of the control device 23 due to aging or environmental changes.

[0060] Step S200: Receive the frequency signal output by the liquid level detection circuit 22.

[0061] In this step, when the liquid appliance 100 enters the working state requiring liquid level detection, the liquid level detection circuit 22 starts working, generating a frequency signal of the corresponding frequency based on the liquid level in the cavity 10, and outputting it to the control device 23. The control device 23 receives this frequency signal through its input interface. After receiving the frequency signal, the control device 23 can acquire and process the signal through external interrupts, input capture, or timer input. For example, the control device 23 can configure a certain GPIO pin to external interrupt mode, triggering an interrupt when the rising edge of the frequency signal arrives, and counting and measuring the time of the pulses in the interrupt service routine.

[0062] Step S300: Detect the frequency signal to obtain the second measurement frequency.

[0063] In this step, the control device 23 uses its internal timer to measure the frequency of the received frequency signal to obtain a second measured frequency. The second measured frequency refers to the frequency value of the output signal of the liquid level detection circuit 22 obtained by the control device 23 based on its internal clock. Due to the frequency deviation of the internal clock of the control device 23, the second measured frequency may deviate from the true frequency of the output signal of the liquid level detection circuit 22.

[0064] The method for obtaining the second measurement frequency by detecting the frequency signal is similar to the method for obtaining the first measurement frequency by detecting the reference signal, and the periodic measurement method or other suitable methods can be used.

[0065] To improve measurement accuracy and reliability, in some embodiments, the control device 23 performs multiple detections on the frequency signal to obtain a third detection sequence containing multiple detection frequency values. For example, the control device 23 continuously measures the frequency signal 10 times to obtain a third detection sequence containing 10 frequency values. Then, the control device 23 performs data processing on the third detection sequence, such as removing the maximum and minimum values ​​to obtain a fourth detection sequence. Removing the maximum and minimum values ​​can effectively eliminate abnormal values ​​caused by transient interference, measurement jitter, etc. Next, based on the fourth detection sequence, a second measurement frequency is calculated. The calculation method can be the arithmetic mean, weighted average, or median, etc. Using the arithmetic mean method can effectively reduce random errors and improve the repeatability and stability of the measurement. In some embodiments, during data processing, if the dispersion of each value in the third detection sequence is too large (e.g., the standard deviation exceeds a preset threshold), the control device 23 can determine that the measurement is abnormal, discard the measurement result, and remeasure the frequency signal to improve the reliability of the final second measurement frequency.

[0066] Step S400: Calibrate the second measurement frequency based on the calibration coefficient to obtain the third measurement frequency.

[0067] In this step, the control device 23 uses the calibration coefficient obtained in step S100 to perform calibration calculations on the second measurement frequency to obtain the calibrated third measurement frequency. The third measurement frequency refers to the frequency value after calibration compensation. This frequency value has eliminated the influence of the internal clock frequency deviation of the control device 23 and can truly reflect the actual frequency of the output signal of the liquid level detection circuit 22.

[0068] Step S500: Determine the liquid level of the liquid appliance 100 based on the third measurement frequency.

[0069] In this step, the control device 23 determines the current liquid level in the cavity 10 based on the calibrated third measurement frequency and the pre-established correspondence between the third measurement frequency and the liquid level. The correspondence between the third measurement frequency and the liquid level can be established in various ways, such as by lookup table or mathematical formula. If a lookup table is used, when the third measurement frequency is not at the exact frequency point in the lookup table, the control device 23 can calculate the corresponding liquid level value using methods such as linear interpolation, polynomial interpolation, or spline interpolation.

[0070] After determining the liquid level, the control device 23 can execute corresponding control actions based on the liquid level value. For example, in a washing machine application, if the current liquid level is detected to be lower than the target liquid level, the control device 23 will control the water inlet valve to open to add water; if the liquid level reaches or exceeds the target liquid level, the control device 23 will control the water inlet valve to close to stop water intake. In a coffee machine application, if the water tank level is detected to be lower than the minimum working liquid level, the control device 23 will trigger a water shortage alarm, reminding the user to add water, and will prohibit the heating and extraction functions from starting to protect the equipment safety.

[0071] In some embodiments, the control device 23 can continuously monitor the liquid level and display the liquid level information on the display screen or indicator light of the liquid-using appliance 100, allowing the user to understand the liquid level status in real time. In smart appliances, the control device 23 can also upload the liquid level information to a cloud server or send it to the user's smartphone APP via a wireless communication module (such as WiFi, Bluetooth, Zigbee, etc.) to achieve remote monitoring and intelligent management.

[0072] Through the above-described liquid level detection method, this application achieves high-precision liquid level detection based on software calibration. Without increasing hardware costs, it can effectively eliminate systematic errors caused by clock frequency deviation of control device 23, and significantly improve the accuracy of liquid level detection and product consistency.

[0073] In some embodiments, a second measurement frequency is calibrated based on a calibration coefficient to obtain a third measurement frequency, including but not limited to steps S410 to S420. Step S410: Calculate a second ratio between the second measurement frequency and the calibration coefficient; Step S420: Use the second ratio as the third measurement frequency.

[0074] Specifically, the third measurement frequency is calculated using the following formula: F3 = F4 / K; Where K is the calibration coefficient, F3 is the third measurement frequency, and F4 is the second measurement frequency.

[0075] If K=0.9975 and F4 is 44.481Hz, then F3=44.481 / 0.9975 =44.592481Hz.

[0076] In some embodiments, to reduce computational load, the reciprocal of the calibration coefficient can be pre-calculated and stored. During calibration calculation, the second measurement frequency is directly multiplied by the reciprocal of the calibration coefficient, thereby converting the division operation into a multiplication operation and improving computational efficiency.

[0077] Through the above calibration calculations, even if there are differences in the internal clock frequency of the control device 23 in different batches, the third measurement frequency obtained after calibration can accurately reflect the true frequency of the output signal of the liquid level detection circuit 22, thereby ensuring the consistency of liquid level detection between different products.

[0078] As another aspect of the embodiments of this application, the embodiments of this application provide a control device 23, including: a processor, and a memory communicatively connected to the processor; the memory stores computer program instructions executable by the processor, which, when executed by the processor, cause the control device 23 to perform the method as described in any one of the embodiments of the first and second aspects.

[0079] Specifically, such as Figure 5 As shown, the control device 23 includes at least one processor 231 and a memory 232 connected in communication. Figure 5 Taking a bus system connection and a processor 231 as an example. Understandably, the various components in the control device 23 are coupled together through a bus system, which is used to achieve communication between the components. It is easy to understand that the bus system, in addition to the data bus, can also include a power bus, a control bus, and a status signal bus, etc. However, for clarity and brevity, in... Figure 5 The general refers to all buses as bus systems. This is understandable. Figure 5 The structures shown in the embodiments are merely illustrative and do not limit the structure of the mobile terminal 100 described above. For example, the mobile terminal 100 may also include components that are more... Figure 5 The structure shown has more or fewer components, or has the same as Figure 5 The diagram shows different configurations of the structure.

[0080] Specifically, processor 231 provides computational and control capabilities to support control device 23 in executing corresponding business logic, such as supporting control device 23 in executing the methods provided in the embodiments of this application, or executing the steps in any possible implementation of the methods provided in the embodiments of this application. Those skilled in the art will understand that processor 231 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0081] Memory 232, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, instructions, and modules, such as the programs, instructions, and modules corresponding to the methods in the embodiments of this application. In some embodiments, memory 232 may include a program storage area and a data storage area. The program storage area may store an operating system, an application program required for at least one function, and the data storage area may store data created according to the use of processor 231. Processor 231 executes various functional applications and data processing of control device 23 by running non-transitory software programs, instructions, and modules stored in memory 232 to implement the methods provided in the embodiments of this application, or to perform the steps in any possible implementation of the methods provided in the embodiments of this application. In some embodiments of this application, memory 232 may include high-speed random access memory and may also include non-transitory memory. For example, at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory 232 may also include memory remotely located relative to processor 231, and these remotely located memories may be connected to processor 231 via a communication network. It is understood that examples of the aforementioned communication networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0082] As can be understood from the foregoing, the implementing entity of any method provided in the embodiments of this application can be any suitable type of mobile terminal 100 with certain computing and control capabilities, such as the control device 23 described above. In some feasible implementations, any method provided in the embodiments of this application can be implemented by a processor executing computer program instructions stored in a memory.

[0083] As another aspect of the embodiments of this application, see Figure 2 This application embodiment also provides a liquid level detection circuit board 20, including a substrate 21, a liquid level detection circuit 22, and a control device 23 as described in the third aspect; the liquid level detection circuit 22 is electrically connected to the control device 23, and the liquid level detection circuit 22 and the control device 23 are disposed on the substrate 21.

[0084] The control device 23 has the same structure and function as the control device 23 described in any of the above embodiments, and will not be described in detail here.

[0085] As another aspect of the embodiments of this application, this application provides a liquid-using appliance 100, including a cavity 10 and a liquid level detection circuit board 20 as described in the fourth aspect; the cavity 10 is configured to contain liquid; the liquid level detection circuit board 20 is configured to detect the liquid level in the cavity 10.

[0086] The liquid level detection circuit board 20 has the same structure and function as the liquid level detection circuit board 20 described in any of the above embodiments, and will not be described in detail here.

[0087] By adopting the liquid level detection circuit board 20 provided in this application, the accuracy and consistency of liquid level detection in liquid-using household appliances 100 can be improved, effectively eliminating systematic errors caused by clock frequency deviation of the control device, significantly improving product performance stability and user experience, while not increasing hardware costs and enhancing the product's market competitiveness.

[0088] As another aspect of the embodiments of this application, see Figure 6 This application provides a liquid level calibration system 1000, including a calibration device 200 and a liquid level detection circuit board 20 as described in the fourth aspect; the calibration device 200 is electrically connected to the liquid level detection circuit board 20; the calibration device 200 is configured to output a reference signal to the liquid level detection circuit board 20.

[0089] The liquid level detection circuit board 20 has the same structure and function as the liquid level detection circuit board 20 described in any of the above embodiments, and will not be described in detail here.

[0090] The electrical connection between the calibration device 200 and the liquid level detection circuit board 20 can be achieved in several ways. In one embodiment, the calibration device 200 is connected to a test point or connector on the liquid level detection circuit board 20 via a dedicated test fixture or probe. In another embodiment, the liquid level detection circuit board 20 has a dedicated calibration interface (e.g., pin header, spring pin header, or connector), and the calibration device 200 is connected to this calibration interface via a connecting cable.

[0091] The liquid level calibration system 1000 is typically deployed at specific workstations on the production line (such as final inspection stations or dedicated calibration stations), and can also be configured in service centers. In production line applications, the liquid level calibration system 1000 can be integrated with a production management system (MES) to automatically record calibration data for each circuit board (such as serial number, calibration coefficient, calibration time, operator number, etc.), establishing a complete product quality traceability system. By analyzing the statistical distribution of batch calibration data, the stability of the production process can be monitored, abnormal fluctuations can be detected in a timely manner, and corrective measures can be taken. In some embodiments, the liquid level calibration system 1000 can also be configured as a portable device, carried by field service engineers to the customer's site for periodic calibration or troubleshooting of installed liquid-using appliances, extending product lifespan and maintaining optimal performance.

[0092] This specialized liquid level calibration system 1000 ensures that each liquid level detection circuit board 20 is precisely calibrated to obtain accurate calibration coefficients, thereby guaranteeing the consistency and reliability of batches of liquid-using household appliances.

[0093] In some embodiments, the calibration device 200 includes a signal generation module and a detection module; the signal generation module is electrically connected to the detection module and the liquid level detection circuit board 20 respectively; wherein, the signal generation module is configured to generate a reference signal; in response to the detection module detecting that the actual frequency of the reference signal is equal to a first frequency value, the signal generation module outputs the reference signal to the liquid level detection circuit board 20; in response to the detection module detecting that the actual frequency of the reference signal is not equal to the first frequency value, the signal generation module does not output the reference signal to the liquid level detection circuit board 20.

[0094] The specific structure of the signal generation module can refer to existing technologies, such as a chip based on a numerically controlled oscillator or a direct digital frequency synthesizer. By programming and setting the output frequency, it can generate square wave or sine wave signals with precisely adjustable frequencies. The first frequency value is the preset target frequency value of the reference signal, such as 40Hz.

[0095] The detection module is typically implemented using a high-precision frequency meter, whose measurement accuracy should be significantly higher than that of the liquid level detection circuit board 20 to be calibrated.

[0096] In this embodiment, the detection module monitors in real time, and only outputs the reference signal to the device under calibration when the frequency meets the accuracy requirements. This ensures the accuracy of the calibration benchmark from the source and avoids systematic deviations caused by errors in the calibration device itself. Furthermore, this automatic detection and judgment mechanism eliminates human error, avoids the risk of using unqualified reference signals for calibration, and ensures that each calibration is based on an accurate benchmark, significantly improving the calibration success rate and consistency.

[0097] As another aspect of the embodiments of this application, the embodiments of this application also provide a computer-readable storage medium storing computer-executable instructions for causing an electronic device to perform the methods provided in the embodiments of this application.

[0098] In some embodiments, the storage medium may be a memory such as FRAM, ROM, PROM, EPROM, EEPROM, flash memory, magnetic surface memory, optical disk, or CD-ROM; or it may be a variety of devices including one or any combination of the above-mentioned memories.

[0099] In some embodiments, executable instructions may take the form of a program, software, software module, script, or code, written in any form of programming language (including compiled or interpreted languages, or declarative or procedural languages), and may be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0100] As an example, executable instructions may, but do not necessarily, correspond to files in the file system. They may be stored as part of a file that holds other programs or data, for example, in one or more scripts in a Hyper Text Markup Language (HTML) document, in a single file dedicated to the program in question, or in multiple collaborative files (e.g., a file that stores one or more modules, subroutines, or code sections).

[0101] As an example, executable instructions can be deployed to execute on a single computing device (including devices such as smart terminals and servers), or on multiple computing devices located in one location, or on multiple computing devices distributed across multiple locations and interconnected via a communication network.

[0102] As another aspect of the embodiments of this application, the embodiments of this application also provide a computer program product, the computer program product including a computer program stored on a computer-readable storage medium, the computer program including program instructions, which, when executed by a computer, cause the computer to perform the method as described in the foregoing embodiments.

[0103] It should be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0104] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a general-purpose hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for at least one computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this application as described above, which are not provided in detail for the sake of brevity; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A calibration method for a liquid level detection circuit board, characterized in that, The calibration method includes: Receive the reference signal output by the calibration device; The reference signal is detected to obtain the first measurement frequency; Obtain the actual frequency of the reference signal; The calibration coefficient of the liquid level detection circuit board is determined based on the actual frequency and the first measurement frequency.

2. The calibration method according to claim 1, characterized in that, The determination of the calibration coefficient of the liquid level detection circuit board based on the actual frequency and the first measurement frequency includes: Calculate the first ratio between the first measured frequency and the actual frequency; The first ratio is used as the calibration coefficient.

3. The calibration method according to claim 1 or 2, characterized in that, The calibration method further includes: Store the calibration coefficients.

4. A liquid level detection method, characterized in that, The liquid level detection method is applied to a control device, wherein the control device is disposed on a liquid level detection circuit board, the liquid level detection circuit board further includes a liquid level detection circuit, the liquid level detection circuit board is disposed on a liquid-using household appliance, and the liquid level detection method includes: The calibration coefficient of the liquid level detection circuit board is obtained based on the calibration method described in any one of claims 1-3. Receive the frequency signal output by the liquid level detection circuit; The frequency signal is detected to obtain the second measurement frequency; The second measurement frequency is calibrated based on the calibration coefficient to obtain the third measurement frequency; The liquid level of the liquid-using appliance is determined based on the third measurement frequency.

5. The liquid level detection method according to claim 4, characterized in that, The step of calibrating the second measurement frequency based on the calibration coefficient to obtain the third measurement frequency includes: Calculate the second ratio between the second measurement frequency and the calibration coefficient; The second ratio is used as the third measurement frequency.

6. A control device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer program instructions executable by the processor, which, when executed by the processor, cause the control device to perform the method as described in any one of claims 1-5.

7. A liquid level detection circuit board, characterized in that, Includes a substrate, a liquid level detection circuit, and the control device as described in claim 6; The liquid level detection circuit is electrically connected to the control device, and the liquid level detection circuit and the control device are disposed on the substrate.

8. A liquid-cooled household appliance, characterized in that, Includes a cavity and a liquid level detection circuit board as described in claim 7; The cavity is configured to contain liquid; The liquid level detection circuit board is configured to detect the liquid level in the cavity.

9. A liquid level calibration system, characterized in that, Includes a calibration device and a liquid level detection circuit board as described in claim 7; The calibration device is electrically connected to the liquid level detection circuit board; The calibration device is configured to output the reference signal to the liquid level detection circuit board.

10. The liquid level calibration system according to claim 9, characterized in that, The calibration device includes a signal generation module and a detection module; The signal generation module is electrically connected to the detection module and the liquid level detection circuit board, respectively. The signal generation module is configured to generate the reference signal; In response to the detection module detecting that the actual frequency of the reference signal is equal to the first frequency value, the signal generation module outputs the reference signal to the liquid level detection circuit board; In response to the detection module detecting that the actual frequency of the reference signal is not equal to the first frequency value, the signal generation module does not output the reference signal to the liquid level detection circuit board.

11. A computer storage medium, characterized in that, The computer storage medium stores instructions or programs that, when executed by at least one processor, cause the at least one processor to perform the method as described in any one of claims 1 to 5.

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