A liquid level detection circuit and apparatus
Patent Information
- Application Number
- CN202522117939.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2026-09-25
- Estimated Expiration
- 2035-09-30
AI Technical Summary
[0002]在饮水设备中，需要对水箱内的水位进行实时地监测，目前常用的液位检测方式中，浮球式液位检测的缺点是在某些特定结构的箱体内无法安装且容易发生机械偏移，降低液位检测的精度，电容式液位检测的缺点是容易受电磁干扰等外界环境的影响，超声波液位检测的缺点是检测器件成本价格高
[0024]本申请提供了一种液位检测电路和装置，其中，控制芯片的液位检测输出端和液位检测反馈端以及高液位检测探针的第一端均与液位检测电容的第一端连接，液位检测电容的第二端与公共探针的第一端且接地，高液位检测探针的第二端设置于待测箱体内的预设高液位高度，公共探针的第二端低于待测箱体内的预设低液位高度，且预设低液位高度低于预设高液位高度。若待测箱体内的液位不低于预设高液位高度，那么液位检测电容充电完成后通过高液位检测探针、待测箱体内的液体以及公共探针所构成的回路进行快速放电，控制芯片可在不受液位检测电容的第一端的电压检测精度的影响下基于液位检测电容的放电速度准确确定待测箱体的液位高度。
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Figure CN224802496U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of liquid level detection technology, and in particular to a liquid level detection circuit and device. Background Technology
[0002] In drinking water equipment, it is necessary to monitor the water level in the water tank in real time. Among the commonly used liquid level detection methods, the disadvantages of float-type liquid level detection are that it cannot be installed in certain specific tank structures and is prone to mechanical displacement, which reduces the accuracy of liquid level detection. The disadvantages of capacitive liquid level detection are that it is easily affected by external environmental factors such as electromagnetic interference. The disadvantage of ultrasonic liquid level detection is that the detection device is expensive.
[0003] Therefore, how to detect the liquid level in the water tank is a problem that urgently needs to be solved by those skilled in the art. Utility Model Content
[0004] The purpose of this invention is to provide a liquid level detection circuit and device. If the liquid level in the test tank is not lower than the preset high liquid level height, the liquid level detection capacitor will be charged and then discharged quickly through the circuit formed by the high liquid level detection probe, the liquid in the test tank, and the common probe. The control chip can accurately determine the liquid level height of the test tank based on the discharge speed of the liquid level detection capacitor without being affected by the voltage detection accuracy of the first end of the liquid level detection capacitor.
[0005] To solve the above technical problems, this utility model provides a liquid level detection circuit, comprising:
[0006] The control chip has a liquid level detection output terminal connected to the first terminal of a liquid level detection capacitor and a liquid level detection feedback terminal connected to the first terminal of the liquid level detection capacitor. The control chip is used to charge the liquid level detection capacitor and determine the relationship between the liquid level in the test box and the preset high liquid level height based on the discharge rate of the liquid level detection capacitor.
[0007] The liquid level detection capacitor has its first terminal connected to the first terminal of the high liquid level detection probe, and its second terminal grounded.
[0008] The high liquid level detection probe, the second end of the high liquid level detection probe is set at the preset high liquid level height in the test box;
[0009] A common probe, the first end of which is connected to the second end of the liquid level detection capacitor, the second end of which is lower than the preset low liquid level height in the test chamber, and the preset low liquid level height is lower than the preset high liquid level height.
[0010] Preferably, it further includes:
[0011] A liquid level detection resistor, wherein the first end of the liquid level detection resistor is connected to the liquid level detection output terminal of the control chip, and the second end of the liquid level detection resistor is connected to the first end of the liquid level detection capacitor.
[0012] Preferably, it further includes:
[0013] A liquid level feedback resistor, wherein the first end of the liquid level feedback resistor is connected to the liquid level detection feedback terminal of the control chip, and the second end of the liquid level feedback resistor is connected to the first end of the liquid level detection capacitor.
[0014] Preferably, it further includes:
[0015] A first switching circuit has a first terminal connected to the liquid level detection output terminal of the control chip, a second terminal connected to the first terminal of the liquid level detection capacitor, and a control terminal connected to the control signal output terminal of the control chip. The first switching circuit is used to conduct when the control chip charges the liquid level detection capacitor, based on the control of the control chip.
[0016] Preferably, it further includes:
[0017] The second switching circuit has a first terminal connected to the liquid level detection feedback terminal of the control chip, a second terminal connected to the first terminal of the liquid level detection capacitor, and a control terminal connected to the control signal output terminal of the control chip. It is used to conduct based on the control of the control chip after the control chip has finished charging the liquid level detection capacitor.
[0018] Preferably, the control chip is a microcontroller.
[0019] Preferably, the liquid level detection output terminal of the control chip is an I / O port, and the liquid level detection feedback terminal of the control chip is an I / O port with analog-to-digital conversion function.
[0020] Preferably, it further includes:
[0021] An anti-reverse diode is provided, with its first end connected to the liquid level detection output terminal of the control chip and its second end connected to the first end of the liquid level detection capacitor.
[0022] To solve the above-mentioned technical problems, this utility model provides a liquid level detection device, which includes multiple liquid level detection circuits as described above, and the preset high liquid level heights corresponding to each high liquid level detection probe in each of the liquid level detection circuits are different.
[0023] Preferably, the control chip in each of the liquid level detection circuits is the same control chip, and the common probe in each of the liquid level detection circuits is the same common probe.
[0024] This application provides a liquid level detection circuit and device. The liquid level detection output terminal and feedback terminal of the control chip, as well as the first terminal of the high liquid level detection probe, are all connected to the first terminal of the liquid level detection capacitor. The second terminal of the liquid level detection capacitor is connected to the first terminal of a common probe and grounded. The second terminal of the high liquid level detection probe is set at a preset high liquid level height within the test chamber. The second terminal of the common probe is lower than a preset low liquid level height within the test chamber, and the preset low liquid level height is lower than the preset high liquid level height. If the liquid level within the test chamber is not lower than the preset high liquid level height, after the liquid level detection capacitor is fully charged, it rapidly discharges through the circuit formed by the high liquid level detection probe, the liquid within the test chamber, and the common probe. The control chip can accurately determine the liquid level height of the test chamber based on the discharge speed of the liquid level detection capacitor, regardless of the voltage detection accuracy of the first terminal of the liquid level detection capacitor. Attached Figure Description
[0025] To more clearly illustrate the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0026] Figure 1 This is a schematic diagram of the structure of a liquid level detection circuit provided in this application;
[0027] Figure 2 This application provides a schematic diagram of the specific structure of a liquid level detection circuit.
[0028] Figure 3 This is a schematic diagram of the structure of a liquid level detection device provided in this application. Detailed Implementation
[0029] The core of this utility model is to provide a liquid level detection circuit and device. If the liquid level in the test box is not lower than the preset high liquid level height, the liquid level detection capacitor will be charged and then discharged quickly through the circuit formed by the high liquid level detection probe, the liquid in the test box, and the common probe. The control chip can accurately determine the liquid level height of the test box based on the discharge speed of the liquid level detection capacitor without being affected by the voltage detection accuracy of the first end of the liquid level detection capacitor.
[0030] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0031] Please refer to Figure 1 , Figure 1 This application provides a schematic diagram of a liquid level detection circuit, which includes:
[0032] Control chip 1, the liquid level detection output terminal of control chip 1 is connected to the first terminal of liquid level detection capacitor C, and the liquid level detection feedback terminal of control chip 1 is connected to the first terminal of liquid level detection capacitor C, used to charge liquid level detection capacitor C, and determine the relationship between the liquid level in the test box and the preset high liquid level height based on the discharge rate of liquid level detection capacitor C.
[0033] A liquid level detection capacitor C is connected to the first end of a high liquid level detection probe L1, and the second end of the liquid level detection capacitor C is grounded.
[0034] High liquid level detection probe L1, the second end of which is set at a preset high liquid level height in the test chamber;
[0035] The common probe L0 has its first end connected to the second end of the liquid level detection capacitor C. The second end of the common probe L0 is lower than the preset low liquid level height in the test chamber, and the preset low liquid level height is lower than the preset high liquid level height.
[0036] Existing technologies for detecting liquid levels in the test chamber are not very accurate but are costly. Therefore, in this application, the common probe L0 and the high-level probe L1 in the liquid level detection circuit are inserted deep into the test chamber, with different heights. The second end of the common probe L0 is lower than the preset low liquid level height in the test chamber, while the second end of the high-level probe L1 is set at the preset liquid level height, which is lower than the preset high liquid level height. Therefore, when the liquid level in the test chamber is not lower than the preset high liquid level height, the second end of the high-level probe L1 and the second end of the common probe L0 are connected through the conductivity of ions in the liquid within the test chamber. However, if the liquid level in the test chamber is lower than the preset high liquid level height, the second end of the high-level probe L1 is exposed to air and cannot connect to the second end of the common probe L0.
[0037] It should be noted that the preset high liquid level and preset low liquid level can be the liquid level when the liquid volume in the test chamber accounts for a preset proportion of the total volume of the test chamber. For example, the preset high liquid level is the liquid level when the liquid volume accounts for 80% of the total volume of the test chamber, and the preset low liquid level is the liquid level when the liquid volume accounts for 20% of the total volume of the test chamber. This application does not limit this.
[0038] Furthermore, the liquid level detection capacitor C in the liquid level detection circuit is connected in parallel with the circuit between the high liquid level detection probe L1 and the common probe L0. For example, when the liquid level in the test tank is not lower than the preset high liquid level height, the sum of the impedance of the high liquid level detection probe L1, the impedance of the common probe L0, and the impedance of the liquid conducting electricity in the test tank is set as the equivalent resistance R. The unit of the equivalent resistance R at this time is between k ohms and m ohms. Alternatively, when the liquid level in the test tank is lower than the preset high liquid level height, the sum of the impedance of the high liquid level detection probe L1, the impedance of the common probe L0, and the impedance of the air in the test tank is set as the equivalent resistance R, and the equivalent resistance R at this time is equivalent to infinity. Then, the liquid level detection capacitor C is connected in parallel with the equivalent resistance R, and the liquid level detection output terminal and the liquid level detection feedback terminal of the control chip 1 are connected to the first terminal of the liquid level detection capacitor C. Control chip 1 charges the liquid level detection capacitor C through the liquid level detection output terminal, and then stops charging the liquid level detection capacitor C. When the liquid level in the test tank is not lower than the preset high liquid level height, the liquid level detection capacitor C discharges rapidly through the equivalent resistance R determined by the sum of the impedance of the high liquid level detection probe L1, the impedance of the common probe L0, and the impedance of the liquid conducting electricity in the test tank. When the liquid level in the test tank is lower than the preset high liquid level height, the liquid level detection capacitor C discharges slowly through the equivalent resistance R determined by the sum of the impedance of the high liquid level detection probe L1, the impedance of the common probe L0, and the impedance of the air in the test tank, or even does not discharge. The liquid level detection feedback terminal of control chip 1 determines whether the liquid level in the test tank is not lower than the preset high liquid level height based on the voltage difference and discharge time of the first terminal of the liquid level detection capacitor C before and after discharge. It should be noted that, since the impedance of the air inside the test chamber is higher than that of the liquid inside, even if the liquid in the test chamber is pure water, the impedance of pure water is lower than that of air. Therefore, as long as the liquid level in the test chamber is not lower than the preset high liquid level height, the discharge rate of the liquid level detection capacitor C is higher than the discharge rate of the liquid level detection capacitor C when the liquid level in the test chamber is lower than the preset high liquid level height. Compared to directly energizing the high liquid level detection probe L1 and the common probe L0 to determine the relationship between the liquid level in the test chamber and the preset high liquid level height by detecting the voltage at the first end of the high liquid level detection probe L1 or the first end of the common probe L0, this application achieves higher accuracy by using a liquid level detection capacitor C and determining the relationship between the liquid level in the test chamber and the preset high liquid level height based on the discharge rate of the liquid level detection capacitor C.
[0039] It should be noted that control chip 1 first outputs a pulse signal with a preset pulse width and a preset voltage value from the liquid level detection output terminal to charge the liquid detection capacitor. During the charging process, the liquid level detection feedback terminal is in a high impedance state. After charging is completed, the liquid level detection output terminal is in a high impedance state. The liquid level detection feedback terminal of control chip 1 obtains the pre-discharge voltage of the first terminal of the liquid detection capacitor. Subsequently, both the liquid level detection output terminal and the liquid level detection feedback terminal are in a high impedance state, and the liquid detection capacitor discharges through the equivalent resistance R. After a preset discharge time, the liquid level detection feedback terminal of control chip 1 obtains the post-discharge voltage of the first terminal of the liquid detection capacitor. Control chip 1 subtracts the post-discharge voltage from the pre-discharge voltage to obtain the discharge voltage, and then divides the discharge voltage by the preset discharge time to obtain the discharge rate of the liquid level detection capacitor C.
[0040] Of course, in order to improve the efficiency of liquid level detection, the preset discharge time can be less than the complete discharge time of the liquid level detection capacitor.
[0041] Specifically, the relationship between the liquid level in the test chamber and the preset high liquid level can be determined based on the relationship between the discharge rate of the liquid level detection capacitor C and the preset rate. The preset rate can be the rate determined by the control chip 1 based on the amplitude and pulse width of the pulse signal and the number of conductive particles in the liquid in the test chamber. This application does not limit this, but when the liquid level in the test chamber is not lower than the preset high liquid level, the discharge rate of the liquid level detection capacitor C is not less than the preset rate, and when the liquid level in the test chamber is lower than the preset high liquid level, the discharge rate of the liquid level detection capacitor C is less than the preset rate.
[0042] In addition, pulse signals can be output according to a preset cycle, thereby detecting the liquid level based on the discharge rate of the liquid level detection capacitor C within multiple cycles. Multiple liquid level detection results are determined by combining the discharge rates of the liquid level detection capacitor C within multiple cycles. A more accurate liquid level detection result is determined by combining the liquid level detection results determined within multiple cycles. For example, if the liquid level in the test tank is determined to be no lower than the preset high liquid level height within five consecutive cycles, then the liquid level in the test tank is determined to be no lower than the preset high liquid level height. However, if the liquid level in the test tank is determined to be no lower than the preset high liquid level height within only one of the five consecutive cycles, while the liquid level in the test tank is lower than the preset high liquid level height in other cycles, then the liquid level in the test tank is determined to be lower than the preset high liquid level height. The result is that there may be a problem of vibration in the test tank within the cycle in which the liquid level in the test tank is no lower than the preset high liquid level height.
[0043] It should be noted that if the internal material of the test chamber is conductive, the high liquid level detection probe L1 and the common probe L0 will not contact the test chamber, and the distance between them will be greater than the preset distance. However, if the internal material of the test chamber is insulating, the high liquid level detection probe L1 and the common probe L0 can contact the test chamber.
[0044] A terminal CN1 and a wiring harness can be provided between the first end of the liquid level detection capacitor C and the first end of the high liquid level detection probe L1, and between the second end of the liquid level detection capacitor C and the first end of the common probe L0, to extend the wiring between the first end of the liquid level detection capacitor C and the first end of the high liquid level detection probe L1, and between the second end of the liquid level detection capacitor C and the first end of the common probe L0, thus facilitating the installation of the liquid level detection circuit.
[0045] In summary, if the liquid level in the test chamber is not lower than the preset high liquid level height, then after the liquid level detection capacitor C is charged, it will discharge rapidly through the circuit formed by the high liquid level detection probe L1, the liquid in the test chamber, and the common probe L0. The control chip 1 can accurately determine the liquid level height of the test chamber based on the discharge speed of the liquid level detection capacitor C without being affected by the voltage detection accuracy of the first end of the liquid level detection capacitor C.
[0046] Based on the above embodiments:
[0047] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the specific structure of a liquid level detection circuit provided in this application.
[0048] As a preferred embodiment, it also includes:
[0049] The liquid level detection resistor R1 has its first end connected to the liquid level detection output terminal of the control chip 1, and its second end connected to the first end of the liquid level detection capacitor C.
[0050] In this embodiment, a liquid level detection resistor R1 is set between the liquid level detection output terminal of the control chip 1 and the first terminal of the liquid level detection capacitor C to limit the charging current of the liquid level detection capacitor C and avoid the liquid level detection capacitor C from being damaged by excessive charging current.
[0051] As a preferred embodiment, it also includes:
[0052] The liquid level feedback resistor R2 has its first end connected to the liquid level detection feedback terminal of the control chip 1, and its second end connected to the first end of the liquid level detection capacitor C.
[0053] In this embodiment, a liquid level feedback resistor R2 is set between the liquid level detection feedback terminal of the control chip 1 and the first terminal of the liquid level detection capacitor C to limit the current when the control chip 1 detects the voltage before and after the discharge of the liquid level detection capacitor C.
[0054] As a preferred embodiment, it also includes:
[0055] The first switching circuit has its first terminal connected to the liquid level detection output terminal of the control chip 1, its second terminal connected to the first terminal of the liquid level detection capacitor C, and its control terminal connected to the control signal output terminal of the control chip 1. It is used to conduct when the control chip 1 charges the liquid level detection capacitor C, based on the control of the control chip 1.
[0056] In this embodiment, a first switching circuit is provided between the liquid level detection output terminal of the control chip 1 and the first terminal of the liquid level detection capacitor C. When the control chip 1 charges the liquid level detection capacitor C, the control chip 1 turns on the first switching circuit to transmit the pulse signal to the liquid level detection capacitor C through the first switching circuit. When the charging is finished, the first switching circuit is turned off to prevent the liquid level detection capacitor C from backflowing current to the control chip 1.
[0057] As a preferred embodiment, it also includes:
[0058] The second switching circuit has its first terminal connected to the liquid level detection feedback terminal of the control chip 1, its second terminal connected to the first terminal of the liquid level detection capacitor C, and its control terminal connected to the control signal output terminal of the control chip 1. It is used to conduct based on the control of the control chip 1 after the control chip 1 has finished charging the liquid level detection capacitor C.
[0059] In this embodiment, a second switching circuit is provided between the liquid level detection feedback terminal of the control chip 1 and the first terminal of the liquid level detection capacitor C. After the control chip 1 finishes charging the liquid level detection capacitor C, the control chip 1 turns on the second switching circuit to collect the voltage of the liquid level detection capacitor C before and after discharge through the liquid level detection feedback terminal and the second switching circuit, thereby determining the discharge rate of the liquid level detection capacitor C. When the control chip 1 is charging the liquid level detection capacitor C, the second switching circuit is turned off to prevent the charging current from flowing into the liquid level detection feedback terminal.
[0060] In a preferred embodiment, the control chip 1 is a microcontroller.
[0061] In this embodiment, the control chip 1 is a microcontroller. The microcontroller not only has multiple ports, but also has a fast data processing speed, which makes it easy to quickly calculate the discharge speed of the liquid level detection capacitor C and determine the liquid level in the test box, thereby improving the liquid level detection efficiency.
[0062] In a preferred embodiment, the liquid level detection output terminal of the control chip 1 is an I / O port, and the liquid level detection feedback terminal of the control chip 1 is an I / O port with analog-to-digital conversion function.
[0063] In this embodiment, the liquid level detection output terminal of the control chip 1 is the I / O port of the microcontroller, which can output a pulse signal to charge the liquid level detection capacitor C. The liquid level detection feedback terminal of the control chip 1 is an I / O port with analog-to-digital conversion function, which can detect the analog voltage at the first terminal of the liquid level detection capacitor C and convert the analog voltage into a digital signal so that the microcontroller can calculate the voltage before and after discharge of the digital signal and determine the discharge rate of the liquid level detection capacitor C.
[0064] It should be noted that when control chip 1 converts the detected analog voltage into a digital signal, it can specifically do the following:
[0065] ADC_V1=V(u)×A / V(m); ADC_V2=V(o)×A / V(m);
[0066] Wherein, ADC_V1 is the digital signal of the voltage before discharge, ADC_V2 is the digital signal of the voltage after discharge, V(u) is the analog signal of the voltage before discharge, V(o) is the analog signal of the voltage after discharge, A is the resolution of the analog voltage sampling at the liquid level detection feedback terminal, and V(m) is the power supply voltage value when the control chip 1 is working normally.
[0067] As a preferred embodiment, it also includes:
[0068] The reverse protection diode D1 has its first terminal connected to the liquid level detection output terminal of the control chip 1, and its second terminal connected to the first terminal of the liquid level detection capacitor C.
[0069] In this embodiment, an anti-reverse diode D1 is also provided at the liquid level detection output terminal of the control chip 1. The anti-reverse diode D1 causes the current to flow from the liquid level detection output terminal of the control chip 1 to the liquid level detection capacitor C, so as to charge the liquid level detection capacitor C and prevent the current from flowing back to the control chip 1 when the liquid level detection capacitor C discharges. In other words, the liquid level detection capacitor C only discharges through the equivalent resistance R, so as to improve the accuracy of the control chip 1 in calculating the discharge rate of the liquid level detection capacitor C, and thus improve the accuracy of determining the liquid level height detection result.
[0070] The anode of the anti-reverse diode D1 is connected to the liquid level detection output terminal of the control chip 1, and the cathode of the anti-reverse diode D1 is connected to the first terminal of the liquid level detection capacitor C.
[0071] Please refer to Figure 3 , Figure 3This is a schematic diagram of a liquid level detection device provided in this application. The liquid level detection device includes multiple liquid level detection circuits as described above, and the preset high liquid level heights corresponding to each high liquid level detection probe L1 in each liquid level detection circuit are different. Figure 3 The two high liquid level detection probes in the test chamber shown are the first high liquid level detection probe L1 and the second high liquid level detection probe L2. L1 and L2 correspond to different preset high liquid level heights, so different liquid levels can be detected.
[0072] The liquid level detection device in this embodiment includes multiple liquid level detection circuits, and the preset high liquid level heights corresponding to each high liquid level detection probe L1 in each liquid level detection circuit are different. For example, the liquid level detection device includes three liquid level detection circuits, and the preset high liquid level heights of these three liquid level detection circuits are the liquid level when the liquid volume accounts for 80% of the total volume of the test tank, the liquid level when the liquid volume accounts for 60% of the total volume of the test tank, and the liquid level when the liquid volume accounts for 40% of the total volume of the test tank. The preset low liquid level heights of these three liquid level detection circuits are all the liquid level when the liquid volume accounts for 20% of the total volume of the test tank. Based on this, the specific range of liquid level in the test tank can be determined by combining the liquid level detection results of different liquid level detection circuits.
[0073] For a detailed description of the liquid level detection device provided by this utility model, please refer to the above embodiments; this utility model will not be described again here.
[0074] In a preferred embodiment, the control chip 1 in each liquid level detection circuit is the same control chip 1, and the common probe L0 in each liquid level detection circuit is the same common probe L0.
[0075] In this embodiment, the same control chip 1 is reused in each liquid level detection circuit. The same control chip 1 calculates the discharge rate of the liquid level detection capacitor C in different liquid level circuits, thereby accurately and efficiently determining the specific range of liquid height in the test tank without the need for data interaction with other control chips 1, thus improving the efficiency of liquid level detection.
[0076] In addition, the common probe L0 was also reused to avoid the problem of too many probes in the test chamber affecting the accuracy of the test results.
[0077] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, article, or apparatus that includes said element.
[0078] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A liquid level detection circuit, characterized in that, include: The control chip has a liquid level detection output terminal connected to the first terminal of a liquid level detection capacitor and a liquid level detection feedback terminal connected to the first terminal of the liquid level detection capacitor. The control chip is used to charge the liquid level detection capacitor and determine the relationship between the liquid level in the test box and the preset high liquid level height based on the discharge rate of the liquid level detection capacitor. The liquid level detection capacitor has its first terminal connected to the first terminal of the high liquid level detection probe, and its second terminal grounded. The high liquid level detection probe, the second end of the high liquid level detection probe is set at the preset high liquid level height in the test box; A common probe, the first end of which is connected to the second end of the liquid level detection capacitor, the second end of which is lower than the preset low liquid level height in the test chamber, and the preset low liquid level height is lower than the preset high liquid level height.
2. The liquid level detection circuit as described in claim 1, characterized in that, Also includes: A liquid level detection resistor, wherein the first end of the liquid level detection resistor is connected to the liquid level detection output terminal of the control chip, and the second end of the liquid level detection resistor is connected to the first end of the liquid level detection capacitor.
3. The liquid level detection circuit as described in claim 1, characterized in that, Also includes: A liquid level feedback resistor, wherein the first end of the liquid level feedback resistor is connected to the liquid level detection feedback terminal of the control chip, and the second end of the liquid level feedback resistor is connected to the first end of the liquid level detection capacitor.
4. The liquid level detection circuit as described in claim 1, characterized in that, Also includes: A first switching circuit has a first terminal connected to the liquid level detection output terminal of the control chip, a second terminal connected to the first terminal of the liquid level detection capacitor, and a control terminal connected to the control signal output terminal of the control chip. The first switching circuit is used to conduct when the control chip charges the liquid level detection capacitor, based on the control of the control chip.
5. The liquid level detection circuit as described in claim 1, characterized in that, Also includes: The second switching circuit has a first terminal connected to the liquid level detection feedback terminal of the control chip, a second terminal connected to the first terminal of the liquid level detection capacitor, and a control terminal connected to the control signal output terminal of the control chip. It is used to conduct based on the control of the control chip after the control chip has finished charging the liquid level detection capacitor.
6. The liquid level detection circuit as described in claim 1, characterized in that, The control chip is a microcontroller.
7. The liquid level detection circuit as described in claim 6, characterized in that, The liquid level detection output terminal of the control chip is an I / O port, and the liquid level detection feedback terminal of the control chip is an I / O port with analog-to-digital conversion function.
8. The liquid level detection circuit according to any one of claims 1-7, characterized in that, Also includes: An anti-reverse diode is provided, with its first end connected to the liquid level detection output terminal of the control chip and its second end connected to the first end of the liquid level detection capacitor.
9. A liquid level detection device, characterized in that, It includes multiple liquid level detection circuits as described in any one of claims 1-8, and the preset high liquid level heights corresponding to each high liquid level detection probe in each of the liquid level detection circuits are different.
10. The liquid level detection device as described in claim 9, characterized in that, The control chip in each of the liquid level detection circuits is the same control chip, and the common probe in each of the liquid level detection circuits is the same common probe.