How electronic scales work

Scales

The practice of measuring weight using specific devices dates back several centuries. Scales play a crucial role in various settings, from industrial production to household needs. With the advancement of technology, the weighing process has become more efficient, with traditional mechanical designs being replaced by electronic mechanisms. The main goal of scales is to provide precise measurements, leading to increased efficiency and optimization of production cycles. Electronic scales have established a strong presence in the market, gradually replacing their mechanical counterparts.

Construction

There are several key components that make up the electronic mechanism, including sensors, indicators, and a keyboard. It is also possible to construct electronic scales on your own.

The primary function of the scales is to measure the force exerted on the device when an object is placed on the weighing pan. This force is transmitted to a sensor, which is a flexible and tightly connected element that converts the deformation into an electronic signal.

There are multiple varieties of transducers used in electronic scales:

• String transducers employ the vibrations of a tightly stretched metal string within the sensor. The output is determined by the level of force exerted on the string. Manufacturing such a transducer is a complex process, making it less commonly used. Additionally, external factors such as temperature, humidity, and vibration can negatively affect the transducer.
• Piezoquartz transducers rely on changes in frequency of a quartz crystal, which is connected to a flexible component and reacts to applied force. However, the size of the crystal can be affected by environmental factors.
• Deformation is the basis for the action of the sensor in the tensometric type. It is derived from the Latin word and refers to the conversion of the flexible element into electrical resistance. The elastic element, which can be metal plates or rings, is equipped with a spiral of special alloy that acts as the transducer.
• Electronic mechanism scales have another purpose, which is to display objective digital and service material. The indicators on the scales provide visibility of data about the goods, and they also signal any errors that may occur during operation.
• There are three types of indicators available:
• The second category includes liquid crystal segmental and sign-synthesizing indicators. The former rely on liquid crystals and have the advantages of being affordable and energy-efficient, making them suitable for battery-operated scales. However, they are also prone to fragility and tend to malfunction in low temperatures, such as in a cold room. On the other hand, the latter category consists of bitmap matrix indicators that offer the advantage of being able to display various types of data, including ticker-like advertising text. However, these indicators are more expensive and also suffer from fragility and temperature limitations.
• The third category comprises luminescent or gas-discharge sign and segment indicators. These indicators are simple glass neon lamps with multiple anodes arranged in the form of digits or segments.

When an electric current is applied, a digit or its segment of a light bulb illuminates. The specific element that lights up depends on which terminal the current is applied to, and the intensity of the illumination is determined by the magnitude of the current. The color of the glow is controlled by the mixture of gases inside the glass bulb. Due to being manufactured in Russia, gas-discharge indicators are inexpensive, yet they shine brightly and operate reliably in various temperature conditions. Among the drawbacks, fragility, dependency on high voltage, and increased electricity consumption are mentioned.

The keyboard is an integral part of the electronic mechanism of scales. It is used to program the scales, input necessary information about the product and its price. In most models, it is positioned at the bottom of the weighing platform, but there are exceptions where the keyboard is integrated with the display.

Case material

Manufacturers of electronic scales place significant emphasis on the housing to ensure that, in the event of deformation, the device cannot be repaired. The materials commonly used for manufacturing the case include plastic, metal, or glass.

When it comes to desktop scales, manufacturers tend to favor either plastic or glass materials. However, when it comes to industrial floor scales, a more rugged and durable material is needed to withstand heavy loads. That’s why metal is the material of choice for these types of scales. It is highly recommended that the metal casing be either painted or treated with an anti-corrosion agent to ensure longevity.

Internal device

The electronic scales differ significantly from their mechanical counterpart in terms of their design. They are equipped with special frames on the platform that can detect and respond to any movement or action. This means that when a person steps on the scales or places an object on them, the frames subtly deform and display the corresponding weight value, all without being noticeable to the human eye.

The device is equipped with a load cell, a tiny plate that is affixed to its frame. It is connected to three wires that control the resistance. When the device is under load, the frames deform and redistribute the additional weight among each other. The data from each individual device is combined and the total value is computed.

It is crucial to have an understanding that the primary component of floor electronic scales or similar devices’ touch screens is the load cell.

In addition, there is a quadrangular-shaped bridge with a resistor connected to each side. Power is transmitted through one diagonal of the bridge, while the other diagonal carries the parameters. This design of the scales ensures the protection of the sensors against any mechanical harm to them.

What to do if the scales are out of order

There are instances when the electronic device refuses to function. The issue is most likely due to the load cells. Each design has a maximum authorized load set by the manufacturer. If the weight exceeds the permitted limit, the frames become bent and the scales stop working. All that is required is to simply straighten the frames and the device is ready to operate again.

If it is not possible to visually identify the cause of the malfunction, then a tester can be used for diagnosis. In this scenario, the sensor needs to be disconnected from the board and resistance measurements should be taken in all three wires. If the parameters deviate from the normal range in any part of the device, then the cause is identified. Otherwise, the microscopic plate needs to be detached.

Upon opening the device, we discover a copper plate intertwined with wires. Occasionally, a dysfunctional wire may be the root cause of the problem. In such cases, it is sufficient to merely repair the connection. However, the situation can be more severe, where the sensor is no longer functioning correctly and requires replacement. Swapping out the sensor itself is a relatively straightforward task, but it is crucial to recalibrate the scales post-installation. Failure to do so will result in impaired performance.

Calibration

The principle of operation of load cells at the microscopic level is unique and special. Even within the same manufacturing plant and production batch, the bridge connections of the sensors will vary, resulting in a small but present error. Calibration is necessary to eliminate this discrepancy.

If the load cell is calibrated incorrectly or if there is an error in the measurement, it can be removed from the workflow by simply removing the load or by using resistors to simulate the required parameters. This will restore the operation of the mechanism, and since the total mass is calculated by summing the values, accurate measurements can still be obtained.

Alternatively, the faulty element can be disconnected, causing the mechanism to consider its measurement as a zero value.

If you are not a professional, it is still possible for you to identify the cause of the malfunction and repair it yourself with electronic scales, as they are essentially a basic combination of resistors and a circuit board.

The market of contemporary home appliance retailers is filled with an array of options for electronic measuring devices. However, there is a high demand for a limited selection of models from various manufacturers.

The top spot is now taken by the versatile Medisana 40419 TargetScale. These cutting-edge scales come with a hefty price tag of up to 15,000 rubles, making them a luxury purchase. However, they offer unparalleled functionality and convenience. Compatible with Android and IOS devices, users can easily sync the scales with their smartphones or tablets. Unlike traditional scales, the Medisana 40419 TargetScale displays readings right before your eyes, eliminating the need to look down. This innovative device also allows users to track and visualize their weight, fat deposits, blood pressure, body temperature, and sugar levels through graphs. Combining functionality with a sleek design, these scales are truly a dream come true.

SUPRA BSS-6200GN

Coming in second place in terms of popularity is the SUPRA BSS-6200GN electric scale. This option is the most affordable and provides the ability to track not only body weight, but also fat and muscle content. It is particularly sought after by women who are committed to maintaining a healthy lifestyle and following proper nutrition.

Beurer BF-100

The Beurer BF-100 model occupies the third spot. It has virtually no measurement errors. This version features eight electrodes that accurately read and transmit data to a computer and has the capacity to store information for multiple users. The scale platform is constructed using a combination of metal and plastic and also comes with a convenient remote control unit. Its price is approximately eight thousand rubles. However, this model does not enjoy widespread popularity due to negative customer reviews regarding its highly flawed body composition measurement scheme.