A weighing instrument is a device that displays the weight and status of an object being weighed in electronic scales. It is also known as a weighing display. Initially, electronic weighing instruments were analog devices, consisting of components such as an error amplifier, a reversible motor, a balanced bridge, an excitation power supply, a dial, and a pointer. These early systems operated based on the principle of an automatic balance electronic potentiometer, but they had slow weighing speeds, limited functions, and low accuracy, which led to their decline. Today, most weighing displays are digital, offering greater precision and functionality. Composition of the Electronic Weighing Instrument Structural Principle Digital scale instruments come in various types, one of which is illustrated in Figure 1. The digital receiver receives electrical signals from the load cell, which can be either analog or digital. Typically, these signals are small analog voltages, often in the range of tens of millivolts. The circuit principle of the digital display is shown in Figure 2. The excitation power supply provides power to the load cell and serves as a reference voltage for the A/D (analog-to-digital) conversion unit, with stability usually at 0.1% or higher. The amplification unit uses a measuring amplifier structure to receive and amplify the signal from the load cell, with typical gain levels in the hundreds. The filtering unit removes external electrical noise and internal amplifier-generated interference. The A/D conversion unit then transforms the analog signal into a digital one, typically with 14 bits or more of resolution. The data processing unit, centered around a microprocessor, handles tasks like data collection, computation, and storage under program control, before sending the results to the appropriate interface. Finally, the display unit presents the weight value and status in numerical, textual, or graphical formats, and can communicate with external devices through its interface. Schematic Diagram of the Weighing Instrument - Circuit Diagram Performance Characteristics The performance of digital instruments covers five main areas: metrological performance, functionality, environmental adaptability, safety, and reliability. Compared to general-purpose digital weighing instruments, digital displays offer five key features: 1) a built-in sensor excitation power supply, making them user-friendly; 2) ratiometric A/D conversion and frequency multiplication technology, ensuring long-term metrological stability; 3) software that realistically simulates weighing characteristics like vibration, air balance changes, and material drop, resulting in fast, accurate, and stable readings; 4) a parameter setting unit that allows easy adjustment of functions such as tare, zero tracking, calibration, maximum capacity, and indexing, offering strong versatility; 5) output interfaces that enable connection to various external devices, allowing convenient system integration. Accuracy Levels According to OIML Recommendation No. 3, non-automatic scales are divided into four accuracy classes. In China, electronic weighing instruments are also categorized into four grades, labeled I, II, III, and IV. The maximum allowable error for each class is 0.7 times the tolerance of the corresponding instrument class. This classification helps ensure that the instruments meet the required standards for different applications. Netizens Explain the Basic Architectural Principles of Scale Instruments The architecture of a scale instrument is actually quite straightforward. A power supply provides energy to all components. An ADC (Analog-to-Digital Converter) section amplifies the sensor's analog signal and converts it into a digital signal. A central processing unit, commonly referred to as a microcontroller (MCU), processes this digital information. The weight signal is then processed through multiple steps, decoded into a format readable by the display, and shown on the screen. Most instruments include a keyboard for user input, and many have parallel print ports, micro-drive interfaces, RS232 or RS485 communication ports, digital current loop interfaces for large screens, and industrial control-compatible 4–20 mA current loop interfaces for connecting to PLCs. High-end models may even feature CAN bus or Ethernet interfaces. Some instruments also include a USB port, although it is rarely used due to its short transmission range. Therefore, only a few scale instruments incorporate a USB interface. Stay tuned for more updates Tags: electronic weighing instrument, structural principles Previous: The application of single-chip microcomputer in EDM machine Next: How to identify the quality of bathroom hardware accessories Shoe Racks,Black Shoe Racks,Shoes Shop Display Rack,Shoes Rack Stand Changzhou Offistyle Furniture Co., Ltd. , https://www.offistylefurniture.com