JP3696721B2 - How to display measured values on measuring instruments - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for displaying a measured value in a measuring instrument, and more specifically, in a measuring instrument having an A / D conversion circuit, the display of the measured value is changed according to the amount of variation in the A / D conversion. The present invention relates to a method for displaying measured values.
[0002]
[Prior art]
When an analog input signal is converted into a digital signal by an A / D (analog / digital) conversion circuit, even if the analog input signal is constant, the lower 1 of the digital signal is used due to the characteristics of the conversion circuit. Bits can change, which causes the display to wobble, giving the user a sense of uselessness.
[0003]
In order to suppress such fluctuations, the following A / D conversion value averaging process has been conventionally performed. That is, digital signals sequentially output from the A / D conversion circuit at a predetermined sampling interval are stored in a memory such as a RAM, and when the number of digital signals reaches a predetermined number, the average value is calculated and displayed. Send to vessel.
[0004]
In this way, every time a predetermined number of digital signals are collected, the digital signal sent to the display is stabilized by the averaging process that averages these A / D conversion values. As a result, it is possible to suppress fluctuations in the lower digits displayed on the display.
[0005]
[Problems to be solved by the invention]
However, when the analog input signal is fluctuating, inconvenience may occur if such averaging processing is performed. For example, assuming that the averaging process is performed on five A / D conversion values, as shown in FIG. 4, in the process of increasing the analog input signal from 0V to 2V (full scale), t1, Sampling is performed at t2, t3, t4, and t5. It is assumed that the A / D conversion value (count value) at 2 V (full scale) is 10,000.
[0006]
Here, for example, the count value at t1 is 2000, the count value at t2 is 4000, the count value at t3 is 6000, the count value at t4 is 8000, and the count value at t5 is 10,000. When processing is performed,
(2000 + 4000 + 6000 + 8000 + 10000) / 5 = 6000
Thus, where 10000 (2V) is supposed to be displayed, 6000 (1.2V) is displayed, and the true value is not displayed.
[0007]
The present invention has been made to solve such a problem, and an object of the present invention is to perform an averaging process when the analog input signal is relatively stable, and the analog input signal fluctuates. In such a case, there is provided a method for displaying a measured value in a measuring instrument that displays a measured value following the input signal without performing an averaging process.
[0008]
[Means for Solving the Problems]
To achieve the above object, the present invention provides an A / D conversion circuit for converting an analog input signal into a digital signal at a predetermined sampling interval, and a storage means for storing a digital signal output from the A / D conversion circuit. Measured values in a measuring instrument comprising: control means having an arithmetic function for averaging a predetermined number of digital signals stored in the storage means; and display means for displaying measured values sent from the control means In this display method, the control means compares the current data with the previous data each time a digital signal is output from the A / D conversion circuit, and if the fluctuation amount is within a predetermined range, the storage means An averaging process is performed on a predetermined number of digital signals, and the average value is displayed on the display means. When the fluctuation amount is outside the predetermined range, Without performing disproportionation process is characterized by displaying as it said display means said time data.
[0009]
As described above, according to the present invention, when the analog input signal is stable, the averaging process is performed, so that the display fluctuation based on the conversion error of the A / D conversion circuit is prevented. On the other hand, when the analog input signal is fluctuating, the A / D count value for each sampling is displayed as it is as an instantaneous value without performing the averaging process.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, in order to better understand the technical idea of the present invention, embodiments will be described with reference to the drawings.
[0011]
FIG. 1 schematically shows the configuration of a measuring instrument for carrying out the present invention. According to this, the measuring instrument includes, for example, a double integration type A / D conversion circuit 1, an arithmetic circuit 2 including a CPU as a control means, a RAM (random access memory) 3 as a storage means, a display or A display 4 corresponding to a printer is provided, and these are connected to each other by a bus 5.
[0012]
With this as a basic configuration, the operation of the arithmetic circuit 2 will be described with reference to the flowcharts of FIGS. First, in step S1, the averaging processing counter is reset. In this embodiment, it is assumed that the counter is built in the arithmetic circuit 2.
[0013]
The A / D conversion circuit 1 converts an analog input signal into a digital signal at a predetermined sampling interval. In step S2, the A / D conversion circuit 1 determines whether the A / D conversion is completed for each sampling. In step S3, the digital signal from the A / D conversion circuit 1 is fetched as current data.
[0014]
In step S4, it is determined whether the value of the counter for averaging processing is “0”, that is, whether the counter is in an initial state. If the current data is the first data, the process proceeds to step S4a and the first data is stored in the RAM 3. Then, in step S4b, the averaging processing counter is set to "1" and the process returns to step S2. .
[0015]
On the other hand, if the value of the counter for averaging processing is not “0” in step S4, that is, if there is previous data, the previous data is read from the RAM 3 in step S5, and subsequently in step S6, the current data Are compared with the A / D count value of the previous data, and the difference is calculated.
[0016]
In step S7 in the next stage, the arithmetic circuit 2 determines whether the current data fluctuates with respect to the previous data from the difference calculated in step S6. When making this determination, it is determined whether or not the difference calculated in step S6 is within a preset range. The range can be arbitrarily set based on the fluctuation of the analog signal that is the input signal, the accuracy of the measuring instrument considering the conversion error of the A / D conversion circuit itself, and the like.
[0017]
If the arithmetic circuit 2 determines that there is no fluctuation in step S7, it stores the current data in the RAM 3 in step S8, and increases the averaging processing counter by “+1” in step S9. In step S10, it is determined whether the value of the counter for averaging processing has reached a preset value m (for example, “5”).
[0018]
If the value of the counter does not reach the value m in step S10, the arithmetic circuit 2 returns the process to step S2. Thereby, the arithmetic circuit 2 repeats the processing from step S2 to step S9 until m pieces of data are collected in the RAM 3.
[0019]
If the value of the counter reaches the value m in step S10, the arithmetic circuit 2 reads m data stored in the RAM 3 in step S11, and performs an averaging process on the m data in step S12. After that, the average value data is sent to the display 4 in step S13. Then, after the data in the RAM 3 is cleared in step S14, the process returns to step S1.
[0020]
On the other hand, if it is determined in step S7 that there is a change between the current data and the previous data, step S15 is executed, the current data is sent to the display 4, and the process returns to step S1. As a result, the current data that is not averaged is displayed on the display 4 as an instantaneous value as it is.
[0021]
In this way, when the analog input signal is relatively stable, the averaging process is performed to suppress the fluctuation (variation) of the lower digits of the digital display. On the other hand, when the analog input signal is fluctuating, the averaging process is omitted and the instantaneous value is displayed, so that the display can follow the fluctuation of the analog input signal.
[0022]
Further, by performing the averaging process, it is possible to increase the apparent resolution even if a low resolution A / D converter circuit is used. Therefore, it is possible to provide a measuring instrument that is capable of high-resolution display at a low price.
[0023]
Note that the flowcharts shown in FIGS. 2 and 3 are examples, and in the above embodiment, after averaging processing, the contents of the RAM 3 are cleared in step S14. However, as long as the storage capacity of the RAM 3 allows, The conversion data may be stored cumulatively. In addition to simple averaging, various methods such as, for example, a process using a moving average and a process using an indexed average can be applied as the averaging process.
[0024]
【The invention's effect】
As described above, according to the present invention, when the analog input signal is relatively stable, the averaging process is performed. On the other hand, when the analog input signal fluctuates, the averaging process is performed. Since the instantaneous value is displayed immediately without performing it, the fluctuation of the lower digits of the digital display is suppressed, and the true value display following the analog input signal is performed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a basic configuration of a measuring instrument for carrying out the present invention.
FIG. 2 is a flowchart showing a processing procedure of the arithmetic circuit in FIG. 1;
FIG. 3 is a flowchart showing a processing procedure of the arithmetic circuit in FIG. 1;
FIG. 4 is an explanatory diagram for explaining an averaging process when an analog input signal fluctuates in the related art.
[Explanation of symbols]
1 A / D conversion circuit 2 Arithmetic circuit (CPU)
3 Storage device (RAM)
4 Display 5 Bus

Claims (1)

An A / D conversion circuit for converting an analog input signal into a digital signal at a predetermined sampling interval, a storage means for storing a digital signal output from the A / D conversion circuit, and a predetermined number of data stored in the storage means In the measurement value display method in a measuring instrument, comprising: a control means having an arithmetic function for averaging a digital signal; and a display means for displaying a measurement value sent from the control means. Each time a digital signal is output from the A / D conversion circuit, the current data and the previous data are compared. And the average value is displayed on the display means. When the fluctuation amount is outside the predetermined range, Display method of measurement in the measuring instrument and displaying as it said display means data.

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