JPS59119500A - Measuring apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention uses sensors to measure temperature, gas concentration, flow rate, etc.
The present invention relates to measurement devices used in process measurement systems and analysis systems that measure, monitor, analyze, and control the amount of light, etc.

Since the characteristics of sensors used to detect various physical gates in measurement and analysis systems are not perfectly linear, linearizers are essential for measurement devices that process analog signals from sensors. The following types of nearizers are available to compensate for the non-dark blue characteristics of the sensor. Linear approximation circuits constructed using diodes and I
An analog linearizer based on a power series circuit formed using a C multiplier circuit, a digital linearizer formed using a ROM in which linearizer data is tabulated so that A-D conversion data and addresses correspond to each other.
There is a microcomputer-based linearizer that uses the arithmetic function of a microcomputer to perform linearization calculations using a high-order polynomial of an approximation function that approximates the characteristics of a sensor.

The characteristics of the sensor are often convex as shown in FIG. If the sensor characteristics are as shown in Figure 1 (4), when linearizing the sensor signal, 7 = l as shown in Figure 2 (1).
Correction can be made using a correction curve (3) that is symmetrical to the straight line. However, in general, the sensor characteristics differ by several percent F8 even if the sensors are of the same model and have the same measurement range, and the characteristics often become as shown in (2), (3, bar 5, and (6)) in FIG. These instrumental differences often result in 1. It happens. Furthermore, even if the model is the same, if the measurement range is changed, the characteristic curve will have a larger or smaller curvature σ.

Therefore, in the conventional linearizer mentioned above.

Even if the characteristics of the sensor are the same, the degree of curvature of the characteristic curve changes due to the instrumental error of the sensor.
If the characteristics differ even slightly, it becomes necessary to adjust the circuit or create another characteristic equation.

Further, although the adjustment is performed once, readjustment is also required if the characteristics of the sensor change due to aging, parts replacement, etc. after the characteristic equation for mechanism correction has been determined.

This invention is based on the above-mentioned conventional measuring device equipped with a linearizer, which lacks flexibility because it requires readjustment and creation of a new correction characteristic equation for each sensor due to the instrumental error of the sensor in the nonlinear characteristic curve of the sensor. K to eliminate shortcomings
Even when sensors with nonlinear characteristics have large instrumental errors, they can be linearized with uniform precision without the need for complicated readjustments, and even when sensors with different nonlinear characteristics are used one after another, they can be linearized one after another. The object of the present invention is to provide a versatile measuring device capable of compensating for nonlinearity using two linearizing means. In other words, in a measuring device that uses the calculation function of a microcomputer to perform linearization calculations from the correction formula of the correction curve that linearizes the sensor characteristics, several types of correction curves that linearize the sensor characteristics are converted into data. , the stored correction curves can be arbitrarily selected, and the linearization calculation is performed using the stored A/1) conversion value in the correction calculation formula for each selected correction curve. The present invention relates to a measuring device characterized in that sensor signals can be linearized in accordance with the characteristics of a sensor to be compensated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A measuring device that is an embodiment of the present invention will be described below based on the drawings.

FIG. 6 is a block wiring diagram showing the configuration of a measuring device linearization circuit (b) which is an embodiment of the present invention. The amplified analog input signal from the sensor is converted into a digital signal by a converter (J). A
-Output as a D conversion value. ROM (The correction curve written at 1:00 is, for example, the curve whose characteristic of sensor a4 is shown in FIG. 6) Each table is shown as (6) (7) [8) (9) 0* in FIG. 2 corresponding to K.

Each of the tabulated correction curves can be arbitrarily selected by a signal from a control section αQ of a microcomputer operated in response to a selection command α. The A-D converted conversion data is linearized by software calculation in the calculation section 0 of the microcomputer, but the calculation section Q8) creates correction curves (6) (7) that are selected by signals from the control section 0. )(8)(9)
01 correction formula (6') (75 (85 (95 members).
It may be a quadratic equation, a cubic equation, a logarithm, etc.), or a curved line connecting a line or a broken line with these functional equations. The linearized A-D converted data is converted into an analog linear output (a) by the D/A converter, stored in a recorder, and used as an operational output in a measurement or analysis system.

The measuring device according to the present invention is configured as described above.71-
Therefore, even if the sensor has a large instrumental error in its characteristic curve, the correction curve h11 can be selected according to the sensor characteristics, and the sensor signal can be linearized with uniform accuracy. - Generally, the linearity required for the sensor output is about ±2%FS, so the correction curves (6) (7bars 8) (9)045 shown in Figure 2 are made with a curve of 4%FS. Approximately 20 in total! All curves of the characteristic curve of about i15 can be corrected for blood pulverization. Therefore, even when sensors with different characteristic curves are used one after another, linearization can be performed with one measuring device.

According to the present invention, even sensors with nonlinear characteristics having large instrumental errors can be linearized with uniform accuracy without the need for complicated recirculation, and sensors with different nonlinear characteristics can be used one after another. It is possible to provide a versatile measuring device that can compensate for nonlinearity even in cases where

[Brief explanation of drawings]

FIG. 1 is a diagram showing the characteristics of the sensor, and FIG. 2 is a diagram showing its correction curve. FIG. 3 is a block wiring diagram showing the configuration of a measuring device linearization circuit according to an embodiment of the present invention. (l→... linearization circuit O: 1... ~ converter f14)... selection command 0! ☆...Microcomputer control unit 08)...Microcomputer calculation unit OQ...OM registering the correction curve as conversion data θ...D/A converter 4...Analog conversion type output signal

Claims (1)

[Claims] A means for converting an analog nonlinear input signal from a sensor, a means for linearizing the converted digital signal, and a means for D/A converting the linearized digital signal. In a measuring device that records an output analog linear output signal and uses it as an operational output in a measurement or analysis system, the linearizing means is adapted to the nonlinear characteristics of the sensor.
means for storing several kinds of correction curves for linearizing 1 as ~Φ conversion data; means for making it possible to arbitrarily select a correction function stored in the storage means; 2. A measuring device comprising means for performing a linearization calculation based on the converted values stored in the storage means in the correction calculation formula for each correction curve.