A novel photoelectric liquid level sensor
By combining a light guide block with light-emitting and receiving devices, liquid level detection is achieved through total internal reflection and refractive index differences. This solves the problems of easy damage, poor detection accuracy, and limited application of photoelectric liquid level sensors, and achieves structural simplification, cost reduction, and improved detection accuracy, making it suitable for transparent containers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHENZHEN RUILIAN SENSING TECHNOLOGY CO LTD
- Filing Date
- 2025-07-07
- Publication Date
- 2026-07-03
AI Technical Summary
Existing photoelectric liquid level sensors are easily damaged, have poor detection accuracy, are costly, and have limited applications, especially in transparent containers where their integrity must be compromised.
By using a light guide block in conjunction with light-emitting and receiving devices, liquid level detection is achieved through total internal reflection and refractive index differences. This simplifies the structure, avoids the triangular light cone structure, and improves detection accuracy by combining hydrophobic nano-coatings and signal processing.
The simplified structure reduces costs, improves durability and detection accuracy, broadens application scenarios, is suitable for transparent containers without compromising integrity, and meets the needs of automated control.
Smart Images
Figure CN224455920U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of sensor technology, specifically to a novel photoelectric liquid level sensor. Background Technology
[0002] A photoelectric liquid level sensor is an automated device used for liquid level detection. Its core function is to be installed on containers such as water tanks to identify the presence of liquid inside. The sensor then transmits the detection result to a host computer in the form of an electrical signal or protocol signal, thereby enabling automatic control of the liquid level or triggering corresponding actions. These sensors are widely used in the sensor industry, providing key technical support for liquid level monitoring and automated management in various fields such as industrial production, oil pipelines, and liquid consumer electronics.
[0003] The shortcomings of existing technology:
[0004] 1. Structural design flaws: The light path transmission relies on a triangular light cone structure. This structure has an abrupt shape and is easily damaged by external forces such as collisions and friction during installation and use, which reduces the durability and lifespan of the sensor.
[0005] 2. Accuracy issues: The surface of the triangular light cone structure is prone to water droplets. Water droplets can interfere with the refraction and reflection of light, causing the sensor to make a deviation in its judgment of the liquid level, resulting in misjudgment and affecting the reliability of the detection results.
[0006] 3. Cost and installation limitations: The processing and assembly of the triangular light cone structure is relatively complex, which increases the production and manufacturing costs. At the same time, in some application scenarios, it is necessary to drill holes in the container or install a prismatic cone head to adapt to the sensor, which limits its application in scenarios such as transparent water tanks where the integrity of the container does not need to be damaged.
[0007] Therefore, existing technologies have shortcomings and need further improvement. Utility Model Content
[0008] In view of the problems existing in the prior art, this utility model provides a novel photoelectric liquid level sensor.
[0009] To achieve the above objectives, the specific solution of this utility model is as follows:
[0010] This utility model provides a novel photoelectric liquid level sensor, comprising:
[0011] Light-emitting devices used to emit infrared light or laser light;
[0012] A receiving device used to receive optical signals and convert them into electrical signals;
[0013] A light guide block is installed between the light-emitting device, the receiving device, and the liquid container to be tested;
[0014] A signal amplification and processing device is electrically connected to the receiving device;
[0015] The MCU controller is electrically connected to the signal amplification and processing device;
[0016] The end face of the light guide block is installed parallel to and in close contact with the wall of the liquid container to be tested, so as to ensure that the detection area of the light guide block can be completely covered when the liquid reaches the detection position.
[0017] The light guide block is configured such that, in the absence of liquid, the air and the light guide block form a total internal reflection interface, and the emitted light undergoes total internal reflection at the interface between the light guide block and the air and is received by the receiving device.
[0018] When liquid is present, the refractive index of the liquid is close to that of the light guide block, which disrupts the total internal reflection condition. Most of the emitted light is transmitted into the liquid, resulting in a significant reduction in the light signal received by the receiving device.
[0019] Furthermore, the light-emitting device is an infrared light-emitting diode or a laser diode.
[0020] Furthermore, the receiving device is a phototransistor or photodiode, used to convert the received optical signal into an electrical signal.
[0021] Furthermore, the installation angle of the light guide block makes the optical axis angle between the light-emitting device and the receiving device 85°-95° to achieve total internal reflection detection.
[0022] Furthermore, the light guide block is made of a transparent material, and the difference between its refractive index and the refractive index of the liquid to be tested is less than a preset threshold, for example, the difference between the refractive index of the light guide block and the refractive index of the liquid to be tested is ≤0.2.
[0023] Furthermore, the surface of the light guide block is provided with a hydrophobic nano-coating to prevent droplets from adhering and affecting the optical path.
[0024] Furthermore, the signal amplification and processing device includes an amplification circuit and a filtering circuit, used to amplify and filter weak photoelectric signals to improve signal quality and stability.
[0025] Furthermore, the MCU controller has an analog-to-digital conversion function, which converts the analog signal processed by the signal amplification and processing device into a digital signal, and judges according to a preset threshold to output a high-level or low-level signal to indicate the presence or absence of liquid.
[0026] Furthermore, it also includes a light cap, which is mounted on the light-emitting device and the receiving device to control the direction of the light path and ensure that the light propagates and is reflected along a predetermined path.
[0027] Furthermore, the light cap has a hole-like structure for converging the light path, with an aperture of 0.1-0.5 mm and an arrangement density of 50-100 holes per square centimeter, limiting the scattering angle between the emitted light and the received light to less than 10°.
[0028] The technical solution of this utility model has the following beneficial effects:
[0029] 1. Simplified structure and reduced cost: It does not rely on the triangular light cone structure. Liquid level detection is achieved through the cooperation of light guide block and light-emitting and receiving devices, which simplifies the overall structural design, reduces the number of parts and processing difficulty, and significantly reduces production and manufacturing costs.
[0030] 2. Improved durability: By eliminating the abrupt triangular light cone, the overall structure of the sensor is more compact, reducing vulnerable parts and making it less prone to damage from collisions and friction during installation, use, and transportation, thus extending its service life.
[0031] 3. Reduced false alarms and improved detection accuracy: It avoids the problem of water droplets easily adhering to the surface of the triangular light cone, and the optical path is less affected by external interference. Liquid level is determined by the difference in reflection between the light guide block and the air / liquid contact surface. The stable detection logic significantly reduces the probability of false alarms and improves the reliability of liquid level detection.
[0032] 4. Expanding application scenarios: It can be directly applied to containers such as transparent water tanks without drilling holes or installing prismatic cones on the container, and without damaging the integrity of the container. It is suitable for scenarios with high requirements for container sealing and appearance, thus enhancing application flexibility.
[0033] 5. Highly efficient logic: By utilizing the physical differences between the light guide block and air (forming a total reflection interface) and liquid (no total reflection interface, light is directly transmitted), combined with signal processing and MCU control, it can quickly determine the presence or absence of liquid level, with fast response speed, meeting the real-time requirements of automated control. Attached Figure Description
[0034] Figure 1 This is a schematic diagram of the container of this utility model after it has been filled with liquid;
[0035] Figure 2 This is a schematic diagram of the container of this utility model without liquid.
[0036] Attached image captions:
[0037] 1. Light-emitting device; 2. Light cap; 3. Receiving device; 4. Signal amplification and processing device; 5. Light guide block; 6. MCU controller. Detailed Implementation
[0038] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.
[0039] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0040] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0041] In the description of this embodiment, the terms "upper," "lower," "front," "rear," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.
[0042] Combination Figures 1-2 As shown, this utility model provides a novel photoelectric liquid level sensor, comprising:
[0043] Light-emitting device 1 is used to emit infrared light or laser light;
[0044] Receiver 3 is used to receive optical signals and convert them into electrical signals;
[0045] A light guide block 5 is installed between the light-emitting device 1, the receiving device 3, and the liquid container to be tested.
[0046] The signal amplification and processing device 4 is electrically connected to the receiving device 3;
[0047] MCU controller 6 is electrically connected to the signal amplification and processing device 4;
[0048] The end face of the light guide block 5 is parallel to and tightly fitted to the wall of the liquid container to be tested, so as to ensure that the detection area of the light guide block 5 can be completely covered when the liquid reaches the detection position.
[0049] The light guide block 5 is configured such that when there is no liquid, the air and the light guide block 5 form a total internal reflection interface, and the emitted light undergoes total internal reflection at the interface between the light guide block 5 and the air and is received by the receiving device 3.
[0050] When there is liquid, the refractive index of the liquid is close to that of the light guide block 5, which destroys the total internal reflection condition. Most of the emitted light is transmitted into the liquid, resulting in a significant reduction in the light signal received by the receiving device 3.
[0051] The light-emitting device 1 is an infrared light-emitting diode or a laser diode.
[0052] The receiving device 3 is a phototransistor or photodiode, used to convert the received optical signal into an electrical signal.
[0053] The installation angle of the light guide block 5 makes the angle between the optical axis of the light-emitting device 1 and the receiving device 3 85°-95°, so as to achieve total internal reflection detection.
[0054] The light guide block 5 is made of transparent material, and the difference between its refractive index and the refractive index of the liquid to be tested is less than a preset threshold, for example, the difference between its refractive index and the refractive index of the liquid to be tested is ≤0.2.
[0055] The surface of the light guide block 5 is provided with a hydrophobic nano-coating to prevent droplets from adhering and affecting the light path.
[0056] The signal amplification and processing device 4 includes an amplification circuit and a filtering circuit, which are used to amplify and filter weak photoelectric signals to improve signal quality and stability.
[0057] The MCU controller 6 has an analog-to-digital conversion function, which converts the analog signal processed by the signal amplification and processing device 4 into a digital signal, and judges according to a preset threshold to output a high-level or low-level signal to indicate the presence or absence of liquid.
[0058] It also includes a light cap 2, which is installed on the light-emitting device 1 and the receiving device 3 to control the direction of the light path and ensure that the light propagates and is reflected along a predetermined path.
[0059] The light cap 2 has a hole-like structure for converging the light path, with a hole diameter of 0.1-0.5 mm and an arrangement density of 50-100 holes per square centimeter, limiting the scattering angle between the emitted light and the received light to less than 10°.
[0060] The principle of this utility model is as follows:
[0061] Liquid level detection is achieved based on a transmission optical path design and refractive index difference. The specific process is as follows:
[0062] 1. Function of core components
[0063] Light-emitting device 1: emits infrared light or laser light, which enters the light guide block 5.
[0064] Light guide block 5: made of transparent material (such as glass or acrylic), its end face is in close contact with the wall of the container to be tested, guiding light through the container wall, which is made of transparent material.
[0065] Receiver 3: Detects the intensity of the optical signal and converts it into an electrical signal.
[0066] Signal processing module (signal amplification and processing device 4 + MCU controller 6): Signal amplification and processing device 4 amplifies the received signal, and MCU controller 6 compares the light intensity threshold to output the liquid level status.
[0067] 2. Detection principle when there is no liquid
[0068] Optical path behavior:
[0069] The light from the light-emitting device 1 enters the light guide block 5 and reaches the interface between the light guide block 5 and the air inside the container;
[0070] Due to the significant difference between the air refractive index (≈1) and the light guide block 5 (≈1.5), a specular reflection is formed at the interface, and most of the light is reflected back to the receiving device 3.
[0071] Signal output:
[0072] Receiver 3 captures a high light intensity signal, and MCU controller 6 determines that there is "no liquid".
[0073] 3. Detection principle when liquid is present
[0074] Optical path behavior:
[0075] The light reaches the interface between the light guide block 5 and the liquid;
[0076] The refractive index of the liquid (such as water ≈ 1.33) is close to that of the light guide block 5, so no specular reflection occurs at the interface, and the light is directly transmitted into the liquid;
[0077] Receiver 3 receives very little scattered light or ambient noise.
[0078] Signal output:
[0079] The received light intensity decreased significantly, and the MCU controller 6 determined that "there is liquid".
[0080] 4. Anti-interference design
[0081] Light shield - light cap 2: Isolates ambient stray light to ensure that only the reflected / transmitted signals at the interface of light guide block 5 are detected.
[0082] Refractive index matching: When selecting the material for light guide block 5, the following must be met: n represents the refractive index.
[0083] |n light guide block 5−n air | ≫ |n light guide block 5−n liquid |
[0084] To ensure a clear contrast in light intensity between air and liquid states.
[0085] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the protection scope of the present utility model.
Claims
1. A novel optoelectronic liquid level sensor, characterized in that, include: Light-emitting devices, used to emit infrared light or laser light; A receiving device used to receive optical signals and convert them into electrical signals; A light guide block is installed between the light-emitting device, the receiving device, and the liquid container to be tested; A signal amplification and processing device is electrically connected to the receiving device; The MCU controller is electrically connected to the signal amplification and processing device; The end face of the light guide block is installed parallel to and in close contact with the wall of the liquid container to be tested, so as to ensure that the detection area of the light guide block can be completely covered when the liquid reaches the detection position. The light guide block is configured such that, in the absence of liquid, the air and the light guide block form a total internal reflection interface, and the emitted light undergoes total internal reflection at the interface between the light guide block and the air and is received by the receiving device. When liquid is present, the refractive index of the liquid is close to that of the light guide block, which disrupts the total internal reflection condition. Most of the emitted light is transmitted into the liquid, resulting in a significant reduction in the light signal received by the receiving device.
2. The photoelectric liquid level sensor according to claim 1, characterized in that, The light-emitting device is an infrared light-emitting diode or a laser diode.
3. The photoelectric liquid level sensor according to claim 1, characterized in that, The receiving device is a phototransistor or photodiode, used to convert the received optical signal into an electrical signal.
4. The photoelectric liquid level sensor according to claim 1, characterized in that, The installation angle of the light guide block makes the angle between the optical axis of the light-emitting device and the receiving device 85°-95°, so as to achieve total internal reflection detection.
5. The photoelectric liquid level sensor according to claim 1, characterized in that, The light guide block is made of a transparent material, and the difference between its refractive index and the refractive index of the liquid to be tested is less than a preset threshold.
6. The photoelectric liquid level sensor according to claim 1, characterized in that, The surface of the light guide block is coated with a hydrophobic nano-coating to prevent droplets from adhering and affecting the light path.
7. The photoelectric liquid level sensor according to claim 1, characterized in that, The signal amplification and processing device includes an amplification circuit and a filtering circuit, which are used to amplify and filter weak photoelectric signals to improve signal quality and stability.
8. The photoelectric liquid level sensor according to claim 1, characterized in that, The MCU controller has an analog-to-digital conversion function, which converts the analog signal processed by the signal amplification and processing device into a digital signal, and judges according to a preset threshold to output a high-level or low-level signal to indicate the presence or absence of liquid.
9. The photoelectric liquid level sensor according to claim 1, characterized in that, It also includes a light cap, which is mounted on the light-emitting device and the receiving device to control the direction of the light path and ensure that the light propagates and is reflected along a predetermined path.
10. The photoelectric liquid level sensor according to claim 9, characterized in that, The light cap has a hole-like structure for converging the light path, with a hole diameter of 0.1-0.5 mm and an arrangement density of 50-100 holes per square centimeter, limiting the scattering angle between the emitted light and the received light to less than 10°.