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- A little over ten years ago, in the market of load cells used in electronic scales, a new type - quartz piezoresonance load cell (the quartz load cell). Prior to that time in the art, of course, dominated by two types of sensors - vibrochastotny and tensoresistance.
- The main advantage is vibrochastotnogo sensor frequency output signal, it is easy to convert to digital. Disadvantages - significant nonlinearity characteristics of conversion and low-tech, which limits its applicability.
- The main advantage is the high tensoresistance sensor linearity transformation and advanced technology of strain gages. The main disadvantage of this type of sensor is the small output signal, which is difficult to measure with high precision, and only advances in technology specialized analog-to-digital converters provide competitive tensoresistive sensors towards vibrochastotnym and their broad applicability.
- Quartz load cell has emerged as a compromise that combines the advantages mentioned above types of sensors and not have their disadvantages. This sensor has a frequency output with a large deviation of useful and high linearity performance transformation. The process of making quartz piezoelectric elements and production of sensors based on them is not inferior in workability tensoresistance sensors. These potential advantages have allowed for decades to promote this type of load cell from obscurity to the position of one of the most used types vesostroenii. The novelty of the technology and its little-known breeds a lot of fiction in the description of the quartz load cell in the information material on the application of different load cells and their competitive performance.
- For example, some authors allow themselves the following statement, quote: "... the principle of operation, built on the measurement of the frequency of quartz crystal is mechanically connected to an elastic element under the action of the forces applied to it, contains a flaw ...", namely, "... change in the parameters of the crystal can be under the influence of the environment. " But as you know, the sensing element of any type of sensors, it is not protected from the environment, necessarily subject to its influence. For example, the resistance of the strain gauge to a large extent depends on the temperature and humidity of the environment to a greater degree than the resonance frequency of the piezoelectric crystal is dependent on the same parameters. As both gage, and pezorezonator the sensors are protected from the environment, the influence of these parameters is possible at all or any hardware or compensated in software, which is equally good is achieved in one and in the other type.
- Or another example, one of the authors claim that by their physical nature strain sensor based on quartz resonator has unstable characteristics. However, it is well known that quartz - one of the most stable materials in nature, and crystal oscillator, in which the element is used as a frequency control crystal, is one of the most reliable generators in the art. Therefore, just because of their physical nature quartz load cells have a more stable performance than other types of sensors.
- Since it is difficult to suspect respected authors such allegations of incompetence, such statements are dictated apparently competing considerations and generate the very myths.
The reality is this.
- Using quartz load cells can construct electronic scale, resolution of which is ten times or more, and the accuracy of at least three times higher than the same parameters weights built on tensoresistive sensors.
- Quartz load cells - a dynamic technology that has proved its competitiveness. The involvement of a growing number of businesses involved in the production, operation and maintenance of the devices using quartz load cells in a form factor leads to the promotion of this type of transducer by an adequate assessment of their benefits. The same process stimulates further work on improving the technology and products made from its use.
The advantages of multi-band.
- A remarkable property of multiple range instruments is their adaptability - that is, the ability to change the measurement resolution, depending on the mass of cargo weighing for maximum accuracy of weighing.
- For example, the balance of the middle class of accuracy, with a maximum limit of weighing 150 kg and measuring 50 g increments, measure the weight of the goods up to 30 kg with an accuracy better than 0.17% and up to 60 kg is better 0.08% and up to 150 kg is better .033 %.
- For comparison, the tri-band scales with weighing range 30/60/150 kg provide measurement resolution of the mass, respectively, 10/20 / '50 The accuracy of measurement of weight loads up to 30 kg up to 0.033%, up to 60 kg in the same 0.033%, and up to 150 kg remains the same 0.033%. These scales implemented metrology three full scale single-band mid-range accuracy with a maximum weighing capacity are 30 kg, 60 kg and 150 kg.
- Thus, the tri-band scales work successfully for three. Transition from one range of measurement to another is performed automatically scales. Operator actions using multi-band scale, are no different from his actions in the case of the conventional balance.
- The economic effect of multiple range instruments is that they provide in the N-times the width measurement capabilities than conventional scales, thus reducing the cost of solving the problem of measurement in the same N-times (where N - the number ranges). In other words, if a tri-band scales have a price commensurate with the price of single-band of the same weight class, implement the principle of "Three for the price of one."
Article kindly provided by "MERA" - the world leader in industrial use of quartz load cells.
Статья любезно предоставлена компанией "МЕРА" - мировым лидером по промышленному использованию кварцевых тензодатчиков.
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