一、傳感器的選擇

1、 Selection of sensors

本文主要談談傳感器的精度與衡器精度的關系。大家都說“傳感器是衡器的心臟”，這說明衡器的精度和性能不可能超越其使用傳感器的精度和性能。非自動衡器的R76號國際建議的制定早于稱重傳感器OIMLR60號國際建議。由于兩者都是采用分段階梯表示誤差，根據誤差的檢定分度數和檢定分度值來確定器件的大允許誤差（mpe），并以此確定衡器和傳感器的精度級，所以它們之間應滿足以下條件。

This paper mainly talks about the relationship between the accuracy of the sensor and the precision of the weighing instrument. It is said that "the sensor is the heart of the weighing instrument", which shows that the accuracy and performance of the weighing instrument can not exceed the accuracy and performance of the sensor used. International recommendation R76 for non automatic weighing instruments was developed earlier than oimlr60 for load cells. Because both of them use subsection ladder to express the error, the maximum allowable error (MPE) of the device is determined according to the calibration scale and the calibration division value of the error, and then the accuracy level of the weighing instrument and the sensor is determined. Therefore, the following conditions should be met between them.

（1）根據R76的誤差分配，規定傳感器的分量系數為Pi=0.7。傳感器的最大允許誤差，為相應精度及衡器大允許誤差（mpe）的0.7倍。

(1) According to the error distribution of R76, the component coefficient of sensor is defined as pi = 0.7. The maximum allowable error of the sensor is 0.7 times of the corresponding accuracy and the maximum allowable error of the weighing instrument (MPE).

（2）稱重傳感器的最大秤量必須大于衡器的大秤量Max。

(2) The maximum weighing capacity of the load cell must be greater than the maximum weighing capacity max of the weighing instrument.

（3）在整個使用范圍內必須滿足：n≤nmax，v≥vmin，nmax為稱重傳感器的最大檢定分度數。vmin為傳感器的最小檢定分度值，它是由小載荷的溫度影響來決定的。

(3) In the whole application range, it must meet the following requirements: n ≤ nmax, V ≥ Vmin, nmax is the maximum calibration division number of the weighing sensor. Vmin is the minimum calibration value of the sensor, which is determined by the temperature effect of the minimum load.

（4）2DR≤e，其中：DR為傳感器的最小靜載荷恢復值，e為衡器分度值，為首次檢定大允許誤差。

(4) 2DR ≤ e, where Dr is the minimum static load recovery value of the sensor, e is the scale value of the weighing instrument, and is the maximum allowable error of the first verification.

（5）相對DR，即Z=Emax（/2×DR），該比值用來描述多分度秤，由它確定傳感器可使用的不超過最大允差的分度值。相對Y=Emax/Vmin，該比值描述與傳感器容量無關的最大分辨率，即傳感器使用時允許的大分度數。

(5) Relative to Dr, i.e. z = Emax (/ 2 × DR), the ratio is used to describe the multi scale scale, which determines the division value that the sensor can use and does not exceed the maximum tolerance. Relative to y = Emax / Vmin, this ratio describes the maximum resolution independent of the sensor capacity, that is, the maximum number of divisions allowed when the sensor is used.

（6）“稱重傳感器的分級原則，將傳感器劃分為明確的準確度級別，是為了便于傳感器在各種質量測量系統中的應用。本規程（JJG669-2003）的使用中必須識別，一個傳感器的性能可以在使用該傳感器的測量系統中，通過補償而得到改善。因此本規程既不要求傳感器與使用它的稱量系統具有相同的準確度級別，也不要求顯示質量的稱重儀表，使用獲得批準的單的傳感器。”不能正確認識上面的技術條件的內涵，就不可能根據傳感器的技術參數，正確地設計衡器，并會對n≤nmax和v≥vmin兩個制約條件，產生困惑和混亂。

(6) "The grading principle of load cells, which divides sensors into definite accuracy levels, is to facilitate the application of sensors in various quality measurement systems. It must be recognized in the application of this Regulation (jjg669-2003) that the performance of a sensor can be improved by compensation in the measurement system using the sensor. Therefore, this procedure does not require the sensor to have the same accuracy level as the weighing system in which it is used, nor does it require the use of an approved separate sensor for the weighing instrument displaying the quality. " If we can't understand the connotation of the above technical conditions correctly, we can't design the weighing instrument correctly according to the technical parameters of the sensor, which will cause confusion and confusion to the two constraints of n ≤ nmax and V ≥ Vmin.

例如，能不能用nmax=3000的傳感器制作分度數較高于分度數高于3000的衡器？如何根據Z和Y值設計多分度和多量程衡器？這些問題長期以來在衡器界，都是難以得到解答的。由于在有些人的思想中對這些問題已形成了固定的思維模式，要改變起來需要有充足的說明理由。詳盡的說明需要較大的篇幅，我準備另寫一篇文章來詳細說明。

For example, can a sensor with nmax = 3000 be used to make a weighing instrument with a division number higher than or equal to 3000? How to design multi index and multi range weighing instrument according to Z and Y values? For a long time, these problems are difficult to be solved in the weighing instrument field. Since some people have formed a fixed mode of thinking about these problems, we need to have sufficient reasons to change them. A detailed description requires a large space, and I am going to write another article to elaborate.