JP4904797B2 - Electronic balance - Google Patents

Description

  The present invention relates to an electronic balance, and more particularly to an electronic balance having a smoothing function suitable for a use environment.

上式において平滑化処理に必要なデータ数ｋを多くすることにより応答時間（平滑化時間）も長くなるが、平滑化処理後のデータのばらつきが小さくなり測定精度が向上する。
また、ノイズの影響を低減して測定精度を向上させるものとして、特開平６−１０９５２６号公報等に開示されている高次平滑化処理を行うディジタルフィルタも多く用いられている。これらの平滑化処理を行う場合のデータ数は、使用用途や使用環境下に応じて数種類選択可能にしたものもあるが、多くは固定して用いられている。
特開６−１０９５２６号公報 特公平７−１５４０５号公報 特公平６−７６９０８号公報 特公平７−１５４０４号公報 特公平６−９５０４０号公報 Conventionally, in an electronic balance, the analog output of the load-electricity conversion unit is sampled and digitized every predetermined time T by an A / D converter, but this time series data {Xn} is a noise generated by the external environment. In general, a smoothing process is applied because it fluctuates under influence. In this smoothing process, a moving average filter generally shown in the equation (1) is used, and the time series data {Xn} is converted into time series data {Yn}.

Although the response time (smoothing time) is increased by increasing the number k of data necessary for the smoothing process in the above equation, the variation in data after the smoothing process is reduced and the measurement accuracy is improved.
Further, as a means for reducing the influence of noise and improving measurement accuracy, a digital filter that performs high-order smoothing processing disclosed in Japanese Patent Laid-Open No. 6-109526 is often used. The number of data when performing these smoothing processes can be selected from several types according to the intended use and usage environment, but many are fixedly used.
JP-A-6-109526 Japanese Patent Publication No. 7-15405 Japanese Examined Patent Publication No. 6-76908 Japanese Patent Publication No. 7-15404 Japanese Patent Publication No. 6-95040

In conventional electronic balances, the smoothing process as described above is applied. However, the number of smoothing processing means and the number of smoothing process data is fixed or limited to several types. In some cases, the smoothing process may not be suitable for various user requirements and usage environments, making it impossible to perform measurements with appropriate accuracy and responsiveness, reducing the reliability of measurement results and reducing work efficiency. It is also a cause. For this reason, a method of arbitrarily inputting the number of data of the moving average filter with an input key is conceivable. However, a small electronic balance has a problem that a space for adding an input key cannot be taken.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an electronic balance capable of selecting a smoothing process suitable for required measurement accuracy and response time.

In order to achieve the above object, the electronic balance of the present invention converts the load on the dish into an electric signal, smoothes the time series data obtained by A / D converting the electric signal every predetermined time, and the obtained time series. In an electronic balance that computes data and displays a load value, storage medium connecting means for connecting an external storage medium, a data reader for reading smoothing construction data recorded in the storage medium, and the external storage medium And a smoothing processing construction means for automatically constructing a smoothing processing based on the smoothing processing construction data read from the above.
In addition, the electronic balance of the present invention, in which at least one of accuracy, response time, and noise magnitude is designated numerically as the smoothing processing construction data, is configured as described above and requires measurement. It is possible to perform calculation processing for measurement display that adopts smoothing processing suitable for accuracy and response time.

  The electronic balance of the present invention automatically constructs an optimal smoothing processing program by connecting an external storage medium in which the measurement accuracy and response time required by the user are input and set on a personal computer, and provides appropriate measurement accuracy and response. By performing measurement in time, it becomes possible to improve the reliability of measurement results and work efficiency.

The electronic balance provided by the present invention converts the load on the pan into an electric signal, smoothes the time series data obtained by A / D converting the electric signal every predetermined time, and performs arithmetic processing on the obtained time series data. In an electronic balance for displaying a load value, storage medium connecting means for connecting an external storage medium, a data reader for reading smoothing construction data recorded on the storage medium, and the smoothing read from the external storage medium An electronic balance including a smoothing processing construction means for automatically constructing a smoothing processing program based on the processing construction data, wherein the smoothing processing construction means includes, as the smoothing processing construction data , accuracy, response time, A smoothing program is automatically constructed by specifying numerical values of two or more items of noise .

Hereinafter, the electronic balance of the present invention will be described in detail by way of examples. FIG. 1 is a block diagram showing the configuration of the electronic balance of the present invention.
This electronic balance includes a load detection unit 1 that detects a load of an object to be measured and converts it into an electric signal, and an A / D converter 2 that samples the electric signal, performs A / D conversion, and converts it into load measurement data. And various conditions necessary for constructing a smoothing processing program for smoothing the load measurement data, that is, smoothing processing construction data such as measurement accuracy or response time and holding time for holding them are stored. For example, an external storage medium 3 such as a USB memory, a reader 4 that reads the smoothing process construction data recorded by detecting the connection of the external storage medium 3, a general-purpose microprocessor, an interface, and the like, and load measurement data. A processing device 5 for executing a processing program necessary for smoothing and weighing and displaying, a storage device 6 for storing the processing program, and an object to be weighed And a display device 7 for the amount displayed.

  FIG. 2 is a block diagram showing each processing function, which functions when the processing device 5 executes a processing program stored in the storage device 6, for each block. That is, the processing device 5 converts the load measurement data into a smoothing processing function block 51 that performs a smoothing process based on the smoothing process construction data stored in the external storage medium 3, and the load measurement data after the smoothing process. A weight conversion function block 52 that multiplies the weight conversion coefficient to convert the weight value into a weight value, and a smoothing process for constructing a smoothing process program for performing a smoothing process based on the smoothing process construction data input via the reader 4 The process construction function block 53 is provided.

  The smoothing processing construction data is written to the external storage medium 3 by connecting the external storage medium 3 to the personal computer 8 and inputting from the keyboard 9. The reading device 4 detects the connection of the external storage medium 3, reads the smoothing processing construction data written in the external storage medium 3, and inputs the smoothing processing construction data to the processing device 5.

  The smoothing processing construction function block 53 of the processing device 5 includes a program for constructing a variable length moving average filter or a plurality of variable length moving average filters in which the number of data (2k + 1) in equation (1) is variable. When the smoothing processing construction data input from the reading device 4 is received, whether the smoothing processing construction data is only the response time, only the measurement accuracy, or both the response time and the measurement accuracy according to the procedure of the flowchart shown in FIG. Is checked (S1 to S4), and whether to use a single variable length moving average filter for smoothing processing (S5) or to use a plurality of variable length moving average filters (S6), smoothing is selected. Build a processing program.

  FIG. 4 shows the relationship between the measurement accuracy and the response time when only the measurement accuracy of 0.3 mg is input as the smoothing processing construction data, and the measurement accuracy when the sampling cycle of the measurement data is 0.1 sec. And the response time have a relationship as shown in the figure. In the figure, when the measurement accuracy is 0.1 mg, the response time is 16 sec, and when the response time is 1 sec, the measurement accuracy is 0.5 mg. The smoothing processing construction function block 53 storing this characteristic converts the measurement accuracy of 0.3 mg into a smoothing time of 4 sec, and the smoothing time of the smoothing processing program is updated and stored in the storage device 6.

  FIG. 5 shows, for example, the relationship between the measurement accuracy and the response time when the smoothing processing construction data is smoothed with a response time of 1 sec and a measurement accuracy of 0.1 mg. Corresponds to an example of a smoothing processing construction in a case where is not related linearly, and two variable length moving average filters are used. In this case, as shown in FIG. 5A, the smoothing process is performed with a smoothing time of 1 sec for 2 seconds after the load is applied, and thereafter the smoothing process is performed with a smoothing time of 16 sec. As a result, as shown in FIG. 5B, the measured value reaches near the full value of the load in about 2 seconds after the load is applied, and thereafter, the necessary measurement accuracy of 0.1 mg is realized. Can do.

  Next, the smoothing process procedure when the smoothing process construction data shown in FIG. 5 is input will be described based on the flowchart shown in FIG. When the A / D converter 2 converts the electric signal of the load detection unit 1 into load measurement data (S11) and it is determined that the time t from the start of measurement is within 2 seconds (S12), the measurement data Is smoothed for the first smoothing time (1 sec) (S13), and is further multiplied by a weight conversion coefficient to be converted into a weight value (S14). This weight value is displayed on the display device 7 (S15), and this procedure is repeated until 2 seconds. If it exceeds 2 seconds, the measurement data is smoothed in the second smoothing time (16 sec) (S16), and further multiplied by a weight conversion coefficient to be converted into a weight value (S17). This weight value is displayed. It is displayed on the device 7 (S18). Then, it is determined whether or not the initial measurement is started (S19). If the initial measurement is not started, the procedure from S11 is repeatedly executed. When starting over from the initial measurement, after resetting to time t = 0 (S20), the procedure from S11 is repeatedly executed. This determination of the initial measurement start is made by providing an input button for initial measurement start to the processing device 5 for notification or by detecting when the load measurement data has changed more than a certain value and smoothing the signal. This is done by importing into the program.

In addition, when the magnitude of noise included in the input signal is known in advance, when the sampling period is set to 0.1 s by specifying the magnitude of noise, smoothing processing as shown in the following example Is done.
Example 1: When a response time of 1 s and a noise size of ± 0.001 g (a fluctuation width of 0.002 g) are specified, a variable length moving average filter having 10 data is used for smoothing. As a result, the noise of the input signal is decentralized as 0.002 g (1 / √10) and attenuated to 0.0006 g. Components H (X) other than the sampling frequency are attenuated as gain H (X) shown in the following equation (2).
H (X) = (1/10) ΣXi (2)

Example 2: When an accuracy of 0.0001 g and a noise magnitude of ± 0.001 g are specified, the number of data N for obtaining an accuracy of 0.0001 g using only a variable length moving average filter is derived from the following equation (3).
0.002 / √N ≦ 0.00014 (3)
By calculating this, N ≧ 204.08 is derived. Components H (X) other than the sampling frequency are attenuated as shown in the following equation (4).

H (X) = (1/204) ΣXi (4)
Example 3: When an accuracy of 0.0002 g and a response time of 3 s are specified, the number of data N is derived from the following equation (5).
N ≧ (0.002 / 0.00024) ² (5)
As a result, N ≧ 69.44, and 70 data is required. Since the response time is 3 seconds, three variable length moving average filters of 10 data and one variable length moving average filter of 40 data are connected in series.

  In the above embodiment, the smoothing process is performed using the variable length moving average filter. For example, the delay unit 10, the adder 11, and the coefficient units 12a and 12b indicated by the Z conversion symbol in FIG. 7 are used. By storing and registering in advance in the smoothing processing construction function block 53 other digital filters such as an integral filter configured as described above, various filters can be selected and used in accordance with response time and measurement accuracy, It is also possible to execute a more advanced smoothing process.

  The present invention is used for an electronic balance and an electronic balance.

1 is a block diagram showing a schematic configuration of an electronic balance according to the present invention. It is a block diagram which shows the function structure of the processing apparatus 5 concerning an Example. It is a flowchart figure which shows the smoothing filter number discrimination | determination method concerning an Example. It is a figure which shows the smoothing process construction example. It is a figure which shows the smoothing process construction example of smoothing time (A) and measurement precision (B) concerning an Example. It is a flowchart figure which shows the measurement procedure of this electronic balance. It is a block diagram which shows the structure of an integral-type smoothing filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Load detection part 2 A / D converter 3 External storage medium 4 Reading apparatus 5 Processing apparatus 51 Smoothing process functional block 52 Weight conversion functional block 53 Smoothing process construction functional block 6 Storage apparatus 7 Display apparatus 8 Personal computer 9 Keyboard 10 Delay unit 11 Adder 12a Coefficient unit 12b Coefficient unit

Claims (1)

In an electronic balance that converts a load on a plate into an electrical signal, smoothes time series data obtained by A / D conversion of the electrical signal every predetermined time, and performs processing on the obtained time series data to display a load value. Storage medium connecting means for connecting an external storage medium, a data reading device for reading the smoothing process construction data recorded on the storage medium, and a smoothing process based on the smoothing process construction data read from the external storage medium An electronic balance comprising a smoothing processing construction means for automatically constructing a program , wherein the smoothing processing construction means uses numerical values of two or more items of accuracy, response time, and noise as the smoothing processing construction data. An electronic balance that automatically configures a smoothing program by specifying

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