Do you Know the Electronic Scale System?

The development of modern science has put forward new requirements for weighing technology and control in the production process. The electronic scale is a weighing and measuring device equipped with electronic components. It has the characteristics of fast weighing, convenient reading, working under harsh environmental conditions, and easy to combine with computer technology to realize the automation of weighing technology and process control. Therefore, it is widely used in hospitals, schools, enterprises, energy transportation, commercial trade and science and technology. And mini crane scale is required in daily life.

Since the demand of scale is increasing, today we will do some scales introduction.

1.Electronic scale system

Generally, the electronic scale is mainly composed of the following parts:

(1) The load-bearing mechanism and the force-transmitting system, that is, the weighing platform of the electronic scale. It is a system that transmits the weight or force of the object to the weighing sensor, and generally includes: a carrier that accepts the object to be weighed, a scale bridge structure, and a crane hanging connecting parts and limit shock absorbing mechanism, etc.;

(2) The load cell is a converting component that converts the non-electricity (quality) into a conversion element of electricity, which converts the weight or force acting on it basing on a certain functional relationship (usually a linear relationship) into a physical quantity that is easy to measure (usually electricity, such as voltage, current or frequency)

(3) Universal display instrument is the electronic circuit (including amplifier, knife D converter, etc.) and indicator parts (such as display, printing, etc.) that handle the load cell signal;

(4) The power supply is the excitation power supply with high stability to the load cell measuring bridge, which can be AC or DC regulated power supply. The weighing sensor, display component, power supply and other parts, including the analysis and processing of the weight signal are all managed by the core component CPU, collectively referred to the electronic scale controller, which is the center of the electronic scale.

A normal electronic scale system has a user resolution (or count) from 1:3000 to 1:10000. For example, an electronic scale weighing 5 kg and counting 1:10000 has a resolution of 0.5 g. This precision generally refers to an external count. To ensure that the accuracy of external counting is met, electronic scale manufacturers often require the internal resolution of the system to reach a higher order of magnitude. Some standards indicate that the internal system count accuracy should be 20 times the external count accuracy, so in this case, the internal count accuracy must be 1:200,000.

In electronic scale applications, only a small portion of the ADC range is actually used. In general, the full-scale output of the load cell is 6mV. The front end uses a typical 128-fold gain, and the input of the ADC is 770mV at full scale. Therefore, with a standard of 2.5V as reference, only 1/3 of the ADC dynamic range is used. The ADC should have 3 to 4 times internal count accuracy to meet system performance requirements. At this point, the accuracy of the ADC must be 1:800,000 or 19 to 20 bits. Now we can easily understand the complexity of signal processing requirements.

2.Working principle of weighing system 

The weighing instrument detection system mainly consists of: sensing amplifier circuit, data acquisition (analog/digital conversion) circuit, central processing unit, feedback zeroing circuit, external communication and power supply support. The function of the sensing amplification detecting circuit is to convert the weight signal into a micro-variable voltage signal through the strain gauge sensor, and amplify it to a voltage signal suitable for the analog/digital conversion chip and perform A/D conversion.

The systematic error of the meter is mainly generated in this part, so the design of this part is related to the accuracy of the whole system. The central processing unit is responsible for the operation control of the entire system, and performs data processing, automatic correction, automatic range conversion, adaptive sensor replacement, and finally transmits the data to be displayed to the human-computer interaction interface system. External communication refers to a circuit that detects commands and data which transfers between the CPU of the system and the CPU of the human-machine interface system. The power system provides a good power supply for stable operation of the system and provides high-precision arch bridge power.

3.Features of electronic scale

(1) The weighing is convenient, the resolution is high, and the weighing value can be displayed by numbers, so it is convenient for long-distance transmission of signals, achieving the purpose of centralized management and automatic production control.

(2) High precision;

(3) The response speed of the sensor is fast, so the weighing speed is fast;

(4) Good stability, small mechanical wear, long service life and convenient maintenance;

(5) Many sensors have good sealing performance, so they can work in harsh environments;

(6) Due to its simple structure, it is small in size and light in weight. Now the electronic scales have become the mainstream of the development of weighing instruments. They are widely used in industry, commerce and other fields. They are of great significance for improving people's living standards, increasing labor productivity, reducing labor intensity and reducing costs.