CN206353049U - A kind of intelligent electronic-scale system - Google Patents

Abstract

The utility model discloses a kind of intelligent electronic-scale system, belong to daily life technical field, including digital sampling and processing, single-chip microcomputer and liquid crystal display circuit, digital sampling and processing connects single-chip microcomputer, single-chip microcomputer connects liquid crystal display circuit, and digital sampling and processing includes sensor circuit, amplifying circuit and the change-over circuit being sequentially connected.The utility model is amplified filtering process by amplifying circuit to weak voltage signals, converted circuit becomes digital quantity and gives single-chip microcomputer again, single-chip microcomputer controls display circuit to show testee weight by liquid crystal display, the measuring precision is high, weighing is fast, convenient reading, energy-conserving and environment-protective, can work in harsh environments, overcomes the deficiencies such as not strong conditional electronic scale environmental suitability, inadequate hommization, power consumption height.

Description

An intelligent electronic scale system

technical field

The utility model belongs to the technical field of daily life and relates to the direction of electronic scales, in particular to an intelligent electronic scale system.

Background technique

Weighing technology has been valued by people since ancient times and is indispensable in human production and life. Electronic scale is the product of the combination of weighing technology and electronic technology, widely used in industrial production, commercial trade, transportation, machinery manufacturing, medicine and health, aerospace and scientific research and other fields. It has the advantages of fast response, simple structure, small size, light weight, and long life.

Contents of the invention

According to the deficiencies in the prior art above, the technical problem to be solved by the utility model is to propose an intelligent electronic scale system, which amplifies and filters the weak voltage signal through the amplifying circuit, and then converts it into a digital quantity and sends it to the single-chip microcomputer, the single-chip microcomputer The control display circuit displays the weight of the measured object through the LCD screen. The system has high measurement accuracy, fast weighing, convenient reading, energy saving and environmental protection, and can work under harsh environmental conditions. Insufficient power consumption.

In order to solve the above technical problems, the technical solution adopted by the utility model is: an intelligent electronic scale system, the intelligent electronic scale system includes a data collection and processing module, a single-chip microcomputer and a liquid crystal display circuit, the data collection and processing module is connected to the single-chip computer, and the single-chip computer is connected to the liquid crystal display circuit. The display circuit and the data acquisition and processing module include sensor circuits, amplifier circuits and conversion circuits connected in sequence. The sensor circuit uses a four-arm full-bridge circuit connected by four resistance strain gauges R1, R2, R3 and R4. The resistance strain gauges include sensitive The grid, substrate, covering layer and leads, and the strain gauges are symmetrically pasted on the elastic sensitive elements.

In the above system, the amplifying circuit is a dual-channel operational amplifying circuit. The conversion circuit includes an ADA45 chip circuit, an AD791 chip circuit and a resistor R8. The 7 pins of the ADA45 chip are connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the 4 pins of the AD791 chip. The ADA45 chip circuit includes resistors R1, R2, R3, R4, R5, R6, R7, R8, Rg and capacitors C1, C2, resistors R1, R2, R3 and R4 are connected in series, and the connection point of resistors R1 and R3 is connected to the AD791 chip In the circuit, pin 5 of the AD791 chip, the connection point of resistors R2 and R4 are connected to pin 6 of the AD791 chip, the connection point of resistors R3 and R4 is connected to pin 3 of the ADA45 chip, and the connection point of resistors R1 and R2 is connected to the pin of the ADA45 chip 5 pins, the 2 pins of the ADA45 chip are connected to the resistor R5 and the resistor Rg, the other end of the resistor R5 is connected to the AD791 chip circuit through the resistor R7, the two ends of the resistor R5 are connected in parallel with the capacitor C1, and the other end of the resistor Rg is connected through the resistors R6 and R8 Connect the AD791 chip circuit, the two ends of the resistor R6 are connected in parallel with the capacitor C2. The AD791 chip circuit includes resistors R9, R10, R11, R12, capacitors C3, C4, C6, C7, C9, C10, and the transfer interface P1, and the 1, 2, 3 and 4 pins of the transfer interface P1 pass through the resistor R9 respectively. , R10, R11 and R12 are connected to the 2, 1, 10 and 9 pins of the AD791 chip, the 3 and 4 pins of the AD791 chip are respectively connected to the capacitors C3 and C4, and are connected to the ADA45 chip circuit at the same time, and the 5 pins of the ADA45 chip are connected to the capacitor C9, C10 and ADA45 chip circuits, the other end of the capacitor C10 is connected to the 6-pin of the AD791 chip, and the 8-pin of the AD791 chip is connected to the capacitors C6 and C7 respectively.

The beneficial effects of the utility model are: the intelligent electronic scale system provided by the utility model utilizes a high-sensitivity resistance strain sensor to realize object weight information collection, and uses a 24-bit Σ- The Δ-type analog-to-digital converter realizes digital output, and the liquid crystal screen is controlled by a single-chip microcomputer to display the measurement results in real time. The electronic scale has the advantages of simple structure, high measurement accuracy, fast weighing speed, convenient reading, energy saving, environmental protection, and more humanization, and has broad application prospects and popularization value.

Description of drawings

The following is a brief description of the content expressed in the drawings of this specification and the marks in the drawings:

Fig. 1 is a working principle block diagram of an intelligent electronic scale system according to a specific embodiment of the present invention.

Fig. 2 is a structural schematic diagram of a resistance strain gauge according to a specific embodiment of the present invention.

FIG. 3 is a schematic circuit diagram of a four-arm full-bridge circuit according to a specific embodiment of the present invention.

FIG. 4 is a schematic circuit diagram of a conversion circuit according to a specific embodiment of the present invention.

Among them, 1-substrate, 2-sensitive gate, 3-lead, 4-covering layer.

detailed description

Below, referring to the accompanying drawings, through the description of the embodiments, the specific implementation of the present utility model, such as the shape and structure of each component involved, the mutual position and connection relationship between each part, the function and working principle of each part, and manufacturing The process, operation and use methods, etc. are further described in detail to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concept and technical solutions of the present utility model.

As shown in Figure 1-4, an intelligent electronic scale system includes a data acquisition and processing module, a single-chip microcomputer and a liquid crystal display circuit. The data collection and processing module is connected to the single-chip microcomputer, and the single-chip computer is connected to the liquid crystal display circuit. , an amplifying circuit and a conversion circuit, the sensor circuit adopts a four-arm full-bridge circuit connected by four resistance strain gauges R1, R2, R3, R4, and the resistance strain gauge comprises a sensitive grid, a substrate, a covering layer and leads, and the substrate is fixed On the sensitive grid, the leads are connected to the substrate, and the covering layer is located above the substrate to cover the sensitive. The strain gauge is symmetrically pasted on the elastic sensitive element. When the weight is placed on the electronic scale, the sensor circuit outputs an analog voltage signal proportional to the weight of the object, and the weak voltage signal is amplified by the amplifier circuit, and then sent to the A/D conversion circuit. Carry out analog-to-digital conversion (A/D conversion), and then send the converted digital quantity to the single-chip microcomputer. After the single-chip microcomputer receives the data, it processes the data, converts it into quality information, and displays it through the liquid crystal display circuit.

The sensor circuit uses low-cost and high-precision resistance strain gauges. The performance of the sensor determines the accuracy of the entire electronic scale and is one of the core components of the electronic scale. In the figure, R1, R2, R3, and R4 are all resistance strain gauges, and you can choose metal strain gauges of the same specification with higher precision, such as BF350-3AA model constantan foil metal strain gauge, its precision grade is 0.02, and the initial resistance It is 350Ω, the strain limit is 2.0%, and the temperature range is -30℃—150℃. The reason why the four-arm full-bridge circuit is used is mainly because the full-bridge differential circuit has high sensitivity, can perform temperature compensation, and has no nonlinear error. The four-arm full-bridge circuit has converted the weak resistance change sent by the resistance strain gauge into a voltage change without nonlinear error. Since the output voltage signal of the bridge is relatively weak, usually at the millivolt level or even microvolt level, it cannot meet the requirements of A/D The converter has requirements on the signal input level, so it is necessary to select a precision instrument amplifier as the front-end amplifier circuit to obtain a sufficiently high gain and increase the signal amplitude. ADA4528-2 is selected here as a dual-channel operational amplifier circuit, which has a wide operating supply voltage range from 2.2V to 5.5V, high gain, excellent CMRR and PSRR characteristics. The offset voltage is 2.5uV, and the offset voltage drift is 0.015uV/℃. It is especially suitable for low-level precision amplification. It is packaged with 8 pins. When using it, it can be used continuously according to the pin description. It can be powered by batteries. By setting the feedback resistor reasonably, Capacitors form a low-pass filter to limit noise.

The conversion circuit includes an ADA45 chip circuit, an AD791 chip circuit and a resistor R8. The 7-pin of the ADA45 chip is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the 4-pin of the AD791 chip. The ADA45 chip circuit includes resistors R1, R2, R3, R4, R5, R6, R7, R8, Rg and capacitors C1, C2, resistors R1, R2, R3 and R4 are connected in series, and the connection point of resistors R1 and R3 is connected to the AD791 chip In the circuit, pin 5 of the AD791 chip, the connection point of resistors R2 and R4 are connected to pin 6 of the AD791 chip, the connection point of resistors R3 and R4 is connected to pin 3 of the ADA45 chip, and the connection point of resistors R1 and R2 is connected to the pin of the ADA45 chip 5 pins, the 2 pins of the ADA45 chip are connected to the resistor R5 and the resistor Rg, the other end of the resistor R5 is connected to the AD791 chip circuit through the resistor R7, the two ends of the resistor R5 are connected in parallel with the capacitor C1, and the other end of the resistor Rg is connected through the resistors R6 and R8 Connect the AD791 chip circuit, the two ends of the resistor R6 are connected in parallel with the capacitor C2. The AD791 chip circuit includes resistors R9, R10, R11, R12, capacitors C3, C4, C6, C7, C9, C10, and the transfer interface P1, and the 1, 2, 3 and 4 pins of the transfer interface P1 pass through the resistor R9 respectively. , R10, R11 and R12 are connected to the 2, 1, 10 and 9 pins of the AD791 chip, the 3 and 4 pins of the AD791 chip are respectively connected to the capacitors C3 and C4, and are connected to the ADA45 chip circuit at the same time, and the 5 pins of the ADA45 chip are connected to the capacitor C9, C10 and ADA45 chip circuits, the other end of the capacitor C10 is connected to the 6-pin of the AD791 chip, and the 8-pin of the AD791 chip is connected to the capacitors C6 and C7 respectively. As shown in the figure, R1, R2, R3, and R4 are all resistance strain gauges with the same model and specification. When measuring, a heavy object is pressed on the elastic sensitive element, and the elastic sensitive element is deformed, and the strain gauge attached to it is deformed accordingly. , expressed by the amount of change Δ, resulting in a change in resistance, passing through the bridge, and changing the output voltage.

The A/D conversion circuit realizes the conversion from analog signal to digital signal, and sends the sampling coded output of the voltage signal to the control module. In order to achieve high-precision conversion, you can choose a Σ-Δ ADC chip. According to the measurement range and accuracy requirements of the electronic scale, choose the AD7791 chip, which has a built-in 24-bit Σ-Δ ADC, which contains a bufferable or unbuffered differential input, and integrates a differential input amplifier circuit inside. Signal amplification. The AD7791 accepts a differential analog input and a differential reference voltage. It is a low power, complete analog front end suitable for low frequency measurement applications. It typically consumes 65 μA from a 3-V supply and 65 μA from a 5-V supply with buffering disabled. 75μA. Generally speaking, it can meet the requirements of weak signal processing, high precision, simple interface and low power consumption.

STC89C52 chip is selected for single-chip microcomputer, which has the advantages of small size, low power consumption, strong control function, flexible expansion, miniaturization and convenient use, and is widely used in instruments and meters. STC89C52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K in-system programmable Flash memory, which is low in price and can meet the needs of electronic scales. The utility model provides an intelligent electronic scale system based on a resistance strain sensor, which is small in size, light in weight, low in power consumption, accurate in measurement, intuitive in reading, easy to carry, and can meet the weighing needs of people in daily life.

The utility model has been exemplarily described above in conjunction with the accompanying drawings. Obviously, the specific implementation of the utility model is not limited by the above-mentioned methods, as long as various insubstantial improvements are made by adopting the method concept and technical solutions of the utility model, or Directly applying the ideas and technical solutions of the utility model to other occasions without improvement is within the protection scope of the utility model. The protection scope of the present utility model should be determined by the protection scope defined in the claims.

Claims (5)

1. A kind of intelligent electronic scale system, it is characterized in that, described intelligent electronic scale system comprises data collection processing module, single-chip microcomputer and liquid crystal display circuit, data collection processing module connects single-chip microcomputer, single-chip microcomputer connects liquid crystal display circuit, data collection processing module comprises sequentially Connected sensor circuit, amplifying circuit and conversion circuit, the sensor circuit adopts a four-arm full-bridge circuit connected by four resistance strain gauges R1, R2, R3, R4, and the resistance strain gauge includes a sensitive grid, a substrate, a covering layer and a lead , the strain gauge is symmetrically pasted on the elastic sensitive element. 2. The intelligent electronic scale system according to claim 1, wherein the amplifying circuit is a dual-channel operational amplifying circuit. 3. intelligent electronic scale system according to claim 1, is characterized in that, described conversion circuit comprises ADA45 chip circuit, AD791 chip circuit and resistance R8, 7 pins of ADA45 chip are connected one end of resistance R8, the other end of resistance R8 One end is connected to the 4 pins of the AD791 chip. 4. The intelligent electronic scale system according to claim 3, wherein the ADA45 chip circuit includes resistors R1, R2, R3, R4, R5, R6, R7, R8, Rg and capacitors C1, C2, resistor R1 , R2, R3 and R4 in series, the connection point of resistors R1 and R3 is connected to pin 5 of the AD791 chip circuit in the AD791 chip circuit, the connection point of resistors R2 and R4 is connected to pin 6 of the AD791 chip, and the connection point of resistors R3 and R4 is connected to Pin 3 of the ADA45 chip, the connection point of resistors R1 and R2 are connected to pin 5 of the ADA45 chip, pin 2 of the ADA45 chip is connected to resistor R5 and resistor Rg, the other end of resistor R5 is connected to the circuit of the AD791 chip through resistor R7, resistor R5 A capacitor C1 is connected in parallel at both ends of the resistor Rg, the other end of the resistor Rg is connected to the AD791 chip circuit through resistors R6 and R8, and a capacitor C2 is connected in parallel at both ends of the resistor R6. 5. The intelligent electronic scale system according to claim 3, wherein the AD791 chip circuit includes resistors R9, R10, R11, R12, capacitors C3, C4, C6, C7, C9, C10, and an interface P1 , the 1, 2, 3 and 4 pins of the transfer interface P1 are respectively connected to the 2, 1, 10 and 9 pins of the AD791 chip through the resistors R9, R10, R11 and R12, and the 3 and 4 pins of the AD791 chip are respectively connected to the capacitor C3 and C4 are connected to the ADA45 chip circuit at the same time. The 5 pins of the ADA45 chip are connected to the capacitors C9, C10 and the ADA45 chip circuit. The other end of the capacitor C10 is connected to the 6 pins of the AD791 chip. C7.