JPH05203459A - Measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain a measuring apparatus which achieve a generation of calibration data automatically to correct a gain or an offset of an amplifier. CONSTITUTION:A sensor output signal, a reference voltage 7, and an earth 5 are inputted into an amplifier 1 being switched separately with a multiplexer 6. A controller 8 monitors a temperature data and a calibration state flag of a flag memory 10 and also controls the multiplexer 6 and a calibration data computing device 9 to perform a calibration data generation processing based on data of the reference voltage 7 and the earth 5. The calibration data generated is stored into a calibration data memory 4. This eliminates calibrating work and management of the calibration data or the like thereby achieving convenience in the aspect of operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device which amplifies a weak electric signal detected by a sensor and enables data processing.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing a conventional measuring device. In the figure, 1 is an amplifier for amplifying a sensor output signal, 2 is an AD converter for converting the output of the amplifier 1 into digital data, 3 is a correction arithmetic unit for correcting the digital data with temperature data and calibration data, and 4 is the above-mentioned A calibration data memory 5 for storing calibration data is the ground (ground potential) of the amplifier 1 and the AD converter 2.

Next, the operation will be described. The sensor output signal, which is a weak electric signal, is amplified by the amplifier 1 and then A
It is converted into digital data by the D converter 2. The correction calculation device 3 performs a correction calculation on the digital data from the AD converter 2 while referring to the calibration data and temperature data stored in the calibration data memory 4 that have been collected in advance.

Here, the correction calculation is a calculation performed to remove an error caused by a change in the gain and offset of the amplifier 1 depending on temperature. The calibration data is a coefficient used in the correction calculation. The calibration data of the gain is the amplifier 1
Reference voltage (power supply with extremely small voltage fluctuation due to temperature)
The difference between the output at the time of inputting and the output at the time of inputting the ground 5 and the calibration data of the offset are measured by measuring the output at the time of inputting the ground 5 for each temperature, and become the reference value and those values. It is the ratio to the temperature (for example, room temperature 20 ° C.).

The calibration data memory 4 stores, for example, as shown in FIG. 2, a calibration data table having a configuration in which a calibration temperature is associated with an address of the memory and calibration data is stored at that location.

FIG. 9 shows a measuring device using the output signals of a plurality of sensors 0 to n. An amplifier 1 is provided for each sensor output signal, and the output of each amplifier 1 is sequentially output by a multiplexer 11. The AD converter 2 is switched and input.

[0007]

Since the conventional measuring device is constructed as described above, it is necessary to collect the calibration data in advance. Especially, as shown in FIG. 9, the sensor output signal has a plurality of points. In some cases, the management of calibration data becomes complicated. That is, the calibration data is different for each amplifier 1,
When a certain amplifier 1 is replaced due to a failure or the like, it is necessary to collect the calibration data corresponding thereto and store it in the calibration data memory 4 again. In particular, replacement at the site where measurement is performed requires a data input device, which increases the man-hours of workers. Further, there is a problem that the storage and management of the calibration data for each amplifier 1 becomes complicated.

The present invention has been made in order to solve the above-mentioned problems, and calibration data can be obtained without human intervention, and if calibration data is obtained at a certain temperature, the calibration data can be obtained again at that temperature. An object of the present invention is to obtain a measuring device that does not need to obtain calibration data and can be used without making the user aware of the management of calibration data.

[0009]

In a measuring device according to the present invention, temperature data is monitored by a control device, and when a temperature at which calibration data should be obtained is reached, the input of an amplifier is switched to a reference voltage or ground to perform calibration processing. , The calibration data obtained is stored in the calibration data memory, and a calibration status flag is provided for each calibration temperature. I did not try to do it.

[0010]

The controller according to the present invention monitors the temperature data and the calibration status flag and controls the calibration process. Further, once the calibration data is obtained at all the calibration temperatures within the operating temperature range and the calibration table is completed, the calibration process will not be performed thereafter.

[0011]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, parts corresponding to those in FIG. 8 are designated by the same reference numerals, and description thereof will be omitted. In FIG. 1, reference numeral 7 is a reference voltage, 6 is a multiplexer for switching the sensor output signal, the reference voltage 7 and the ground 5 to add to the amplifier 1, and 9 is a calibration data memory for calculating calibration data from digital data from the AD converter 2. Calibration data calculation device to be stored in 4,
Reference numeral 8 is a control device that controls the multiplexer 6 and the calibration data calculation device 9 based on temperature data and a calibration status flag described later, and 10 is a flag memory that stores the calibration status flag as shown in FIG. The control device 8 and the calibration data operation device 9 constitute a control operation device.

Next, the operation will be described. 4 is a flow chart showing the automatic calibration process performed by the control device 8, FIG. 5 is a flow chart showing the details of the calibration process in steps ST2 and ST7 of FIG. 4, and FIG. 6 is a detail of the normal measurement process in step ST4 of FIG. It is a flowchart shown. In FIG. 4, when the measuring device starts operating for the first time, first, in step ST1, all the calibration status flags in the flag memory 10 are cleared by a reset signal.
At the same time, all the gain calibration data in the calibration data memory 4 are reset to "1" and all the offset calibration data are set to "0".

Next, in step ST2, a calibration process as shown in FIG. 5 is performed. First, in step ST21, the multiplexer 6 is switched to input the ground 5 to the amplifier 1. In step ST22, the data obtained by converting the output of the amplifier 1 by the AD converter 2 is temporarily stored in the register in the calibration data arithmetic unit 9 as offset calibration data. Next step S
At T23, the multiplexer 6 is switched to input the reference voltage 7 to the amplifier 1, and the data obtained from the AD converter 2 at this time is taken into the calibration data arithmetic unit 9. Step S
At T24, the calibration data calculation device 9 first performs the step ST2.
The offset calibration data stored in the register in 2 is subtracted from the fetched data, and the subtraction result is divided by the design value of the gain of the amplifier 1. This division result is used as gain calibration data.

In step ST25, the multiplexer 6
Is switched to input the sensor output signal to the amplifier 1, the calibration process is terminated, and the process proceeds to step ST3 in FIG.

In step ST3, the temperature data is fetched, the closest calibration temperature among the preset calibration temperatures is determined, and the address of the determined calibration temperature in the calibration data memory 4 is determined in steps ST22 and ST23. The offset calibration data and the gain calibration data are stored (see FIG. 2), and a calibration status flag is set at the address of the calibration temperature in the flag memory 10 (see FIG. 3).

After obtaining the calibration data as described above,
In step ST4, normal measurement processing as shown in FIG. 6 is performed. First, in step ST41, the multiplexer 6
The data of the sensor output signal obtained from the amplifier 1 and the AD converter 2 is fetched into the correction arithmetic unit 3. In step ST42, the correction arithmetic unit 3 subtracts the offset calibration data stored in the address of the corresponding calibration temperature in the calibration data memory 4 from the above fetched data. Next, in step ST43, the subtraction result is
It is divided by the gain calibration data stored in the address of the corresponding calibration temperature in the calibration data memory 4. The result of the division is output as the final measurement value in step ST44, and the normal measurement process ends.

Next, in step ST5 of FIG. 4, it is monitored whether the temperature data has reached the set calibration temperature,
If the temperature does not reach the calibration temperature, normal measurement processing is continued in step ST4. When the temperature data reaches the calibration temperature, the process proceeds to step ST6, where the flag memory 10 is checked to see if the calibration status flag at that calibration temperature is set.
If the flag is set, it is determined that the calibration is completed and the process returns to step ST4. If the flag is not set, the process proceeds to step ST7 and the calibration process of FIG. 5 is performed again.

The offset calibration data and gain calibration data obtained by the above calibration process are stored in the address of the corresponding calibration temperature in the calibration data memory 4 in step ST8. After that, the normal measurement process of step ST4 is performed using the calibration data.

According to the above, while checking the calibration status flag for each set calibration temperature, the calibration data is automatically calculated for the uncalibrated calibration temperature and stored in the calibration data memory 4.

Example 2. In the first embodiment, the case where the sensor output signal has one data point has been described. However, as shown in FIG. 7, there may be a plurality of sensor output signal data points. In FIG. 7, the output of each amplifier 1 is switched by the multiplexer 6 before being input to the AD converter 2. in this case,
The effect of the present invention is further exerted, and the calibration data for each amplifier 1 is automatically managed, so that the user is not bothered.

[0021]

As described above, according to the present invention, the sensor output signal, the reference voltage, and the ground potential are switched and selected and input to the amplifier, and the flag indicating the presence or absence of the calibration data is checked to find no calibration data. Since it is configured to input the above-mentioned reference voltage and ground potential and create calibration data based on the data at that time, it is possible to automatically create calibration data during measurement and store it in the calibration data memory. Therefore, it is possible to save the user the trouble of collecting the calibration data and to use it without paying any attention to the management of the calibration data.

[Brief description of drawings]

FIG. 1 is a block diagram showing a measuring device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a table stored in a calibration data memory in the same apparatus.

FIG. 3 is a configuration diagram of a table stored in a flag memory in the same device.

FIG. 4 is a flowchart showing an operation of the same device.

FIG. 5 is a flowchart showing a calibration process of the apparatus.

FIG. 6 is a flowchart showing a normal measurement process of the apparatus.

FIG. 7 is a block diagram showing a measuring device according to another embodiment of the present invention.

FIG. 8 is a block diagram showing a conventional measuring device.

FIG. 9 is a block diagram showing another example of a conventional measuring device.

[Description of Reference Signs] 1 amplifier 2 AD converter 3 correction arithmetic unit 4 calibration data memory 5 ground (ground potential) 6 multiplexer 7 reference voltage 8 controller (control arithmetic unit) 9 calibration data arithmetic unit (control arithmetic unit) 10 flag memory

Claims (1)

[Claims] 1. A multiplexer for selecting one of a sensor output signal, a reference voltage and a ground potential, an amplifier for amplifying the output of the multiplexer, and an AD converter for converting the output of the amplifier into digital data. A calibration data memory for storing calibration data for the selected calibration temperature, and digital data obtained from the AD converter when the multiplexer selects the sensor output signal, are read from the calibration data memory according to the temperature at that time. A correction calculation device that corrects using the corrected calibration data, a flag memory that stores a flag indicating whether or not the calibration data has been obtained for the calibration temperature, and the calibration data for the flag that has not been obtained. Is displayed when the multiplexer selects the reference voltage or ground potential. Note: A measuring apparatus comprising: a digital data obtained from an AD converter and calibration data based on a temperature at that time, storing the calibration data in the calibration data memory and processing a flag of the flag memory.