High-precision electronic scale alarm system based on resistive sensor

Abstract

The utility model discloses a high-precision electronic scale alarm system based on a resistive sensor. Comprising a core control module, a sensor module, an analog-to-digital conversion module, a display module, a key module, an alarm module and a power supply module. The sensor module comprises an HL-8 type weighing sensor and a second bearing platform. The bearing platform comprises an upper bearing plate, an upper gasket, a lower bearing plate, a lower gasket and screws. The left side of the top of the HL-8 type weighing sensor is connected with the bottom of the upper bearing plate through the upper gasket and the screw, and the right side of the bottom of the HL-8 type weighing sensor is connected with the top of the lower bearing plate through the lower gasket and the screw, so that an upper suspension distance and a lower suspension distance are formed through the gaskets. The electronic scale alarm system improves the weight measurement precision and stability, has an overload alarm prompt function, and can be suitable for a scene in which the weight of a weighed object needs to be continuously monitored.

Description

Technical Field

[0001] This utility model belongs to the field of weight monitoring technology, and specifically provides a high-precision electronic scale alarm system based on a resistive sensor. Background Technology

[0002] Electronic scales are a new type of instrument in weighing technology, widely used in various applications. The working principle of an electronic weighing system is as follows: a pressure sensor first senses the mass of the object being measured and converts it into a weak electrical signal. Compared to mechanical scales, electronic scales offer advantages such as high measurement accuracy, convenient calibration, strong anti-interference capabilities, diverse functions, intuitive and clear digital display, fast reading speed, compact and lightweight design, waterproof and dustproof protection in some models, better durability, low maintenance costs, wide applicability, and support for intelligent applications (such as IoT connectivity and data recording via an app). They can operate in various environments, transmit weight signals over long distances, easily achieve digital weight display, and connect to computers to automate production processes and improve labor productivity.

[0003] However, because the sensors used for weighing in electronic scales are easily affected by the installation method and the structure of the load-bearing platform, the real-time weight measured is not accurate and stable enough. In addition, electronic scales often only have a single weight measurement function and do not have an overload alarm function, making them unsuitable for scenarios where the weight of the object being weighed needs to be continuously monitored (such as weighing the weight of volatile alcohol in a laboratory, where the weight will decrease if the time is too long). They are not intelligent and user-friendly enough.

[0004] Therefore, there is an urgent need to design a high-precision electronic scale alarm system based on a resistive sensor, so as to improve the measurement accuracy and stability of weight, and to have an overload alarm function. Utility Model Content

[0005] (a) Technical problems to be solved

[0006] Based on this, this utility model proposes a high-precision electronic scale alarm system based on a resistive sensor. This system can improve the measurement accuracy and stability of weight, and has an overload alarm function. It is suitable for scenarios that require continuous monitoring of the weight of the object being measured.

[0007] (II) Technical Solution

[0008] This utility model proposes a high-precision electronic scale alarm system based on a resistive sensor. The high-precision electronic scale alarm system includes a core control module, a sensor module, an analog-to-digital conversion module, a display module, a button module, an alarm module, and a power supply module. The core control module is communicatively connected to the analog-to-digital conversion module, the display module, the button module, and the alarm module. The sensor module is communicatively connected to the analog-to-digital conversion module. The power supply module is connected to the core control module, the analog-to-digital conversion module, and the display module, and the core control module supplies power to the alarm module. The sensor module includes an HL-8 type load cell and a load-bearing platform.

[0009] The load-bearing platform includes an upper load-bearing plate, an upper pad, a lower load-bearing plate, a lower pad, and screws. The top left side of the HL-8 type load cell is connected to the bottom of the upper load-bearing plate through the upper pad and screws, and the bottom right side of the HL-8 type load cell is connected to the top of the lower load-bearing plate through the lower pad and screws, thereby forming an upper and lower suspension distance through the pads.

[0010] Furthermore, the core control module is an STM32 microcontroller, and the analog-to-digital conversion module is a 24-bit A / D converter chip of model HX711.

[0011] Furthermore, the suspension distance is less than 1 cm.

[0012] Furthermore, the load-bearing plate, upper pad, lower load-bearing plate, and lower pad are made of plexiglass made of polymethyl methacrylate.

[0013] Furthermore, the upper and lower load-bearing plates are specifically two circular plates of the same specifications, with a diameter of 10cm and a thickness of 2mm.

[0014] Furthermore, three small screws are evenly installed circumferentially on the circular plate of the lower support plate to serve as a stable base.

[0015] Furthermore, the A+ and A- signal ports of the HX711 24-bit A / D converter chip are connected to the signal output terminal of the HL-8 weighing sensor.

[0016] Furthermore, the STM32 microcontroller is specifically the STM32F103C8T6.

[0017] Furthermore, the display module is an LCD1602 character dot matrix liquid crystal module, and the power module is a portable power source, preferably a power bank.

[0018] Furthermore, the alarm module is a buzzer, and the button module includes buttons S1-S3. Button S1 is used to select the tens digit, units digit, tenths digit, hundredths digit, and thousandths digit of the threshold. Button S2 is used to decrement the number by one digit, and button S3 is used to increment the number by one digit.

[0019] (III) Beneficial Effects

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] This invention relates to a high-precision electronic scale alarm system based on a resistive sensor. It utilizes an STM32 microcontroller, an HL-8 load cell, and an HX711 microcontroller to accurately detect weight. To maintain accuracy during weight measurement, a specially designed load-bearing platform for fixing the HL-8 load cell is incorporated. This platform uses an upper load-bearing plate, upper shims, a lower load-bearing plate, lower shims, and screws to symmetrically connect the HL-8 load cell to both the upper and lower sides. The shims create two suspension distances, one above and one below, allowing for bidirectional vertical displacement between the HL-8 load cell and the upper and lower load-bearing plates. This improves the convenience and stability of weighing operations. Furthermore, the platform is simple to manufacture, low-cost, and easy to implement. In addition, this invention includes a display module, a button module, and an alarm module to provide an overload alarm function, suitable for scenarios requiring continuous weight monitoring during weighing. Attached Figure Description

[0022] The features and advantages of this utility model will be more clearly understood by referring to the accompanying drawings. The drawings are schematic and should not be construed as limiting the utility model in any way. In the drawings:

[0023] Figure 1 This is a system structure diagram of the high-precision electronic scale alarm system based on a resistive sensor in this utility model. The dashed lines in the diagram represent power supply connections, and the solid lines represent signal connections.

[0024] Figure 2 This is a schematic diagram of the connection structure between the HL-8 type weighing sensor and the load-bearing platform in the sensor module of this utility model.

[0025] Figure 3 This is a flowchart of the analog-to-digital conversion system workflow.

[0026] Figure 4 This is the circuit schematic diagram of the analog-to-digital converter module HX711 in this utility model.

[0027] Figure 5 This is a pinout diagram of the STM32F103C8T6 microcontroller of this utility model.

[0028] Figure 6 This is the overall circuit diagram of the alarm system in this utility model. Detailed Implementation

[0029] To make the above-mentioned objectives, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0030] The purpose of this invention is to design an electronic scale that is easy to use in most environments, consistent with weighing devices on the market, capable of accurately measuring the weight of a specified object, and easy to operate and read. Figure 1-6 The diagram shown is a structural block diagram of the high-precision electronic scale alarm system based on a resistive sensor and the circuit diagram of each module in this invention.

[0031] like Figure 1 As shown, this utility model improves upon the design of a high-precision electronic scale alarm system based on a resistive sensor. The high-precision electronic scale alarm system includes a core control module 1, a sensor module 2, an analog-to-digital converter module 3, a display module 4, a button module 5, an alarm module 6, and a power supply module 7. The core control module 1 is communicatively connected to the analog-to-digital converter module 3, the display module 4, the button module 5, and the alarm module 6. The sensor module 2 is communicatively connected to the analog-to-digital converter module 3. The power supply module 7 provides power to the core control module 1, the analog-to-digital converter module 3, and the display module 4. The core control module 1 also provides power to the alarm module 6. The core control module 1 is an STM32 microcontroller system, the analog-to-digital converter module 3 is a 24-bit A / D converter chip of model HX711, and the sensor module 2 includes an HL-8 type weighing sensor 2.1 and a load-bearing platform.

[0032] Sensor module 2 mainly includes a load-bearing platform and an HL-8 type resistance strain gauge sensor. The load-bearing platform includes upper and lower load-bearing plates, gaskets, screws, and nuts. Analog-to-digital conversion module 3 is a 24-bit A / D converter chip - HX711. Power supply module 7 can preferably use a portable power source (such as a power bank). The core control module 1 is a processing system based on an STM32 microcontroller. Display module 4 consists of an LCD1602 display tube, function buttons, LEDs, a buzzer, and other functional components. Sensor module 2 and analog-to-digital conversion module 3 are connected by signal lines, including excitation voltage signals and analog output signals. Other modules are connected via circuit boards. The HL-8 is a cantilever resistance strain gauge pressure sensor with resistance strain gauges attached to both ends of its blind hole. When the cantilever receives downward pressure, the resistance strain gauges deform, changing their resistance and thus changing the output feedback voltage, converting the pressure on the cantilever into voltage data. Its full-scale output voltage = excitation voltage * sensitivity.

[0033] The following section will introduce each module of the entire device, mainly focusing on their functions, parameter configurations, and shape characteristics. This will provide a clearer understanding of how each module works and forms a usable high-precision electronic scale alarm system based on a resistive sensor.

[0034] (1) Hardware introduction and selection of sensor module

[0035] Regarding the selection of sensor module hardware, the sensor required for this invention is a resistive sensor. First, various types of resistive sensors were consulted, and then literature was searched to understand their differences and similarities. Through comparison, a sensor suitable for this design was selected.

[0036] Currently, there are many types of resistive sensors on the market. Classified by the measured quantity, they can be divided into force-sensitive resistors, thermistors, photoresistors, gas-sensitive resistors, and humidity-sensitive resistors; classified by structure and working principle, they can be divided into potentiometer-type, resistance strain gauge-type, and piezoresistive sensors. Based on the requirements, a parallel beam load cell from the resistance strain gauge type was selected for ease of module installation. The HL-8 type load cell, manufactured by Ningbo Keli, is specifically designed for weighing applications.

[0037] The HL-8 load cell boasts high measurement accuracy and is typically available in customizable ranges such as 5kg, 10kg, and 20kg. Manufactured using stainless steel with a passivated surface, and with the circuitry sealed internally using sealant, it exhibits excellent corrosion resistance. This sensor is specifically designed for weighing and is widely used in electronic scales and other similar equipment.

[0038] The relevant technical parameters of the HL-8 type weighing sensor selected in this design are shown in Table 1.

[0039] Table 1 Parameter Specifications of HL-8 Sensor

[0040]

[0041] like Figure 2 As shown, in order to ensure the measurement accuracy of the HL-8 load cell 2.1 and improve the convenience and stability of weighing operations, this utility model improves the design of a load-bearing platform for installing and fixing the HL-8 load cell 2.1. The load-bearing platform includes an upper load-bearing plate 2.2, an upper pad 2.3, a lower load-bearing plate 2.4, a lower pad 2.5, and screws 2.6. The top left side of the HL-8 load cell 2.1 is connected to the bottom of the upper load-bearing plate 2.2 through the upper pad 2.3 and screws 2.6, and the bottom right side of the HL-8 load cell 2.1 is connected to the top of the lower load-bearing plate 2.4 through the lower pad 2.5 and screws 2.6. Thus, two suspension distances (less than 1 cm) are formed above and below through the pads. This suspension distance can ensure that the HL-8 load cell 2.1 and the upper and lower load-bearing plates can achieve bidirectional displacement deformation in the vertical direction, thereby not affecting the measurement accuracy of the weight.

[0042] Furthermore, the support structure, including the load-bearing plate and gaskets, attached to this HL-8 type load cell 2.1 is made of polymethyl methacrylate (PMMA) acrylic. The upper load-bearing plate 2.2 and lower load-bearing plate 2.4 are two identical circular plates, each 10cm in diameter and 2mm thick. Each plate has two drilled holes aligned with the sensor mounting holes, allowing the gaskets to secure the upper and lower load-bearing plates and the sensor. Since both the upper and lower load-bearing plates of this weighing platform can measure weight, two screws of different sized nuts are used to distinguish between the upper and lower sides for mounting the weighing device. The side with the larger nut serves as the base, with three small screws installed on the circular plate to stabilize it. The side with the smaller nut is mounted on the platform side.

[0043] (2) Hardware introduction and selection of analog-to-digital conversion module

[0044] like Figure 3 As shown, the analog-to-digital converter module 3 is a core electronic circuit that converts analog signals into digital signals, abbreviated as ADC. Analog signals refer to continuously changing physical quantities, uninterrupted in both time and amplitude; here, it refers to continuous electrical signals. Digital signals, on the other hand, refer to discrete signals, not continuous; here, it refers to binary digital output electrical signals. To ensure measurement accuracy, selecting an analog-to-digital converter chip with specific functions based on design requirements is crucial. The flowchart of the analog-to-digital converter circuit is shown below. Figure 3 As shown.

[0045] The analog-to-digital conversion module 3 of this invention is specifically the HX711, a 24-bit A / D converter chip designed for high-precision electronic scales. Compared with other chips of the same type, this chip integrates peripheral circuits required by other similar chips, including a regulated power supply and an on-chip clock oscillator, and has advantages such as high integration, fast response speed, and strong anti-interference capability. Therefore, this chip was chosen as the conversion chip for the analog-to-digital conversion module.

[0046] like Figure 4 As shown, the HX711 chip circuit board measures 30mm × 20mm. The left side has six terminals: E+ and E- are power interfaces, and A+ / A- and B+ / B- are two differential signal input ports. Channel A has a built-in programmable amplifier providing a gain of 128 or 64 times; channel B has a gain of 32 times. This invention uses the higher-gain 128 or 64-times channel A, connecting A+ and A- to the signal output terminals of the HL-8 type weighing sensor 2.1, and simultaneously connecting the E+ and E- power supply lines. The right side of the circuit board has four output terminals: VCC is the output voltage of power module 7, GND is the ground terminal, DOUT outputs serial data, and PD_SCK inputs the clock signal. The specific circuit connections for other interfaces follow the standard methods described in the datasheet.

[0047] (3) Hardware introduction and selection of the core control module

[0048] In the control of digital small circuit systems, microcontrollers are the optimal choice. Considering the stringent requirements of this invention regarding the controller's operating speed, accuracy, stability, and sensitivity, after comprehensive comparison, the high-performance, cost-effective 32-bit STM32 microcontroller, the STM32F103C8T6, was ultimately selected as the core controller. This chip adopts the ARM Cortex-M3 core architecture, providing excellent computing performance while maintaining low power consumption. Its package is LQFP48, equipped with 64KB of flash memory and 20KB of random access memory, fully meeting the needs of complex control systems. Compared to traditional 51 series microcontrollers, the STM32 series has significant advantages in computing power and functional integration, making it particularly suitable for embedded applications requiring real-time response. The STM32 microcontroller operates on a 2.0~3.6V supply voltage, can operate within a temperature range of -40°C to 85°C, and its maximum operating frequency is 72MHz. Its pinout is as follows. Figure 5 As shown.

[0049] The STM32 microcontroller consists of six core components: processor core, memory, clock system, peripheral interfaces, power management, and debug and download interfaces. The main control circuit comprises the STM32 microcontroller, a crystal oscillator circuit, and a reset circuit. The crystal oscillator circuit generates the original clock frequency, which, after being amplified or attenuated by a frequency generator, becomes the various bus frequencies used in the computer. The reset circuit is an auxiliary circuit used to return the microcontroller to its initial state, allowing the system to resume operation.

[0050] like Figure 1 and Figure 6 As shown, in order to add overweight alarm prompts and weight threshold setting functions, this utility model is equipped with a button module 5 for setting the weight threshold and an alarm module 6 for prompting overweight alarms. When the weight on the platform exceeds the threshold, the buzzer will sound along with the flashing of the indicator light. The threshold value can be adjusted by pressing the button. The design and wiring of these two modules are conventional designs for those skilled in the art, so they will not be described in detail here.

[0051] (4) Hardware introduction and selection of display module

[0052] There are two options for display devices: digital tube displays and LCD (Liquid Crystal Display) character displays. A digital tube is a semiconductor light-emitting device, its basic unit being a light-emitting diode (LED); an LCD character display is a display device based on liquid crystal technology, specifically designed to display letters, numbers, and custom symbols. Without affecting the display's accuracy, an LCD character display was chosen.

[0053] This invention uses a conventional LCD1602 character dot-matrix liquid crystal module as the liquid crystal display circuit 3, mainly based on its three major advantages: clear and intuitive display, perfectly presenting light intensity data; extremely low power consumption, meeting the energy-saving requirements for long-term system operation; and simple control, requiring only a single-chip microcomputer I / O port for stable driving. The LCD1602 liquid crystal display screen is 70mm long and 30mm wide, and can be used simply by mounting it on the main circuit board. The display screen will show two lines of numbers: the first line is the weight of the measured object, and the second line is the set alarm threshold.

[0054] (5) Selection of power supply module

[0055] There are two common types of power supply in power module 7: one is dry cell battery power, such as a battery box; the other is portable power supply. The system of this utility model is powered by DC power, so power module 7 can be a portable power supply, specifically a power bank.

[0056] To verify the feasibility and measurement accuracy of the alarm system, the following debugging and usage work of the electronic scale alarm system was also carried out:

[0057] After debugging the analog-to-digital conversion module and the display module using the microcontroller, you can start debugging the electronic scale. First, power on the entire device and then press the power switch SW1. The initial interface will appear, and the display will show two lines of characters: the first line is W: 00.000Kg; the second line is Set: 00.000Kg.

[0058] In the display module, the first line of characters represents the weight of the measured object, and the second line is the manually set alarm threshold. Since no alarm threshold has been set during initialization, the alarm circuit is activated, and buzzer B1 sounds along with the flashing alarm indicator D1. Next, the alarm threshold is set as follows: First, press button S3 on the button module. Its function is to shift from left to right in the second line, allowing selection of the tens digit, units digit, tenths digit, hundredths digit, and thousandths digit. When the desired digit is selected using button S3, press buttons S1 and S2 to control the value. S1 decrements the number by one digit, and S2 increments the number by one digit. However, if button S3 is not used to select the target position, pressing buttons S1 and S2 will not produce a numerical response, but the buzzer and alarm indicator will activate. For example, to set the alarm threshold to 12.345 kg from initialization, the operation procedure is as follows: Press the S3 button to select the tens place, then press the S2 button once; press the S3 button again to select the units place, then press the S2 button twice; then press the S3 button to select the tenths place, then press the S2 button three times; next, press the S3 button to select the hundredths place, then press the S2 button four times; finally, press the S3 button to select the thousandths place, then press the S2 button five times. This will achieve the target threshold. To change it to 11.111 kg, follow the same procedure, using the S3 button to select the desired digits sequentially, then using the S1 button to decrease the number.

[0059] When using this electronic scale, simply plug it into a power source and turn on the power switch. The display module has power-off protection and can record the previously set alarm threshold for easy use. Place the object to be measured directly on the platform, and its weight will appear on the screen. We used a Logitech G304 mouse for measurement; Logitech's official weight is 99g; the scale measured 0.099kg, which meets the measurement result and accuracy requirements.

[0060] In addition, the overload alarm function was tested. Since the weighing range of the HL-8 type weighing sensor used in this invention is 10Kg, it is best to set the threshold below this value to protect the sensor device. However, the weight of the mouse measured this time was only 0.099Kg, so the threshold was set below this weight. It was set to 0.088Kg, and the alarm function was tested. The result was that the buzzer sounded along with the flashing alarm indicator light, proving that the overload alarm function of the electronic scale was normal.

[0061] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A high-precision electronic scale alarm system based on a resistive sensor, characterized in that, The high-precision electronic scale alarm system includes a core control module, a sensor module, an analog-to-digital converter module, a display module, a button module, an alarm module, and a power supply module. The core control module is communicatively connected to the analog-to-digital converter module, the display module, the button module, and the alarm module. The sensor module is communicatively connected to the analog-to-digital converter module. The power supply module is connected to the core control module, the analog-to-digital converter module, and the display module, and the core control module supplies power to the alarm module. The sensor module includes an HL-8 type load cell and a load-bearing platform. The load-bearing platform includes an upper load-bearing plate, an upper pad, a lower load-bearing plate, a lower pad, and screws. The top left side of the HL-8 type load cell is connected to the bottom of the upper load-bearing plate through the upper pad and screws, and the bottom right side of the HL-8 type load cell is connected to the top of the lower load-bearing plate through the lower pad and screws, thereby forming an upper and lower suspension distance through the pads.

2. The high-precision electronic scale alarm system based on a resistive sensor according to claim 1, characterized in that, The core control module is an STM32 microcontroller, and the analog-to-digital conversion module is a 24-bit A / D converter chip of model HX711.

3. The high-precision electronic scale alarm system based on a resistive sensor according to claim 1, characterized in that, The suspended distance is less than 1 cm.

4. The high-precision electronic scale alarm system based on a resistive sensor according to claim 3, characterized in that, The load-bearing plate, upper pad, lower load-bearing plate, and lower pad are made of plexiglass made of polymethyl methacrylate.

5. The high-precision electronic scale alarm system based on a resistive sensor according to claim 4, characterized in that, The upper and lower load-bearing plates are specifically two circular plates of the same size, with a diameter of 10cm and a thickness of 2mm.

6. The high-precision electronic scale alarm system based on a resistive sensor according to claim 5, characterized in that, Three small screws are also evenly installed circumferentially on the circular plate of the lower load-bearing plate to serve as a stable base.

7. The high-precision electronic scale alarm system based on a resistive sensor according to claim 2, characterized in that, The A+ and A- signal ports of the HX711 24-bit A / D converter chip are connected to the signal output terminal of the HL-8 weighing sensor.

8. The high-precision electronic scale alarm system based on a resistive sensor according to claim 2, characterized in that, The STM32 microcontroller in question is specifically the STM32F103C8T6.

9. The high-precision electronic scale alarm system based on a resistive sensor according to claim 1, characterized in that, The display module is an LCD1602 character dot matrix liquid crystal module, and the power module is a portable power supply.

10. The high-precision electronic scale alarm system based on a resistive sensor according to claim 1, characterized in that, The alarm module is a buzzer, and the button module includes buttons S1-S3. Button S1 is used to select the tens digit, units digit, tenths digit, hundredths digit, and thousandths digit of the threshold. Button S2 is used to decrement the number by one digit, and button S3 is used to increment the number by one digit.

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