KR100941665B1 - Precision pressure measuring apparatus - Google Patents

Abstract

The present invention is an ultra-precision pressure measuring device, by applying a time difference measurement in parallel with the characteristic of the reciprocal to the conventional frequency measuring method to expand the resolution for the measurement of the frequency output from the frequency output pressure sensor and improve the accuracy It is to let.

The present invention generates an inconsistency between the gate time and the input frequency according to the oscillator for oscillating the reference clock, the frequency counter counting the frequency applied from the pressure sensor according to the reference clock by applying opposite characteristics within the basic resolution, and the reference clock. A time difference measuring unit that calculates the starting point error "A" and the ending point error "B", and then counts the frequencies of the difference parts, and an F / V converter that converts a frequency exceeding the basic resolution integrated by the time difference measuring unit into a voltage value. The A / D converter converts the analog voltage value of the F / V converter into a digital value, the reference clock oscillator controls the oscillation part's reference clock, and converts the digital value applied from the A / D converter into frequency. Compare the integration frequency within the applied basic resolution with the integration frequency for the excess of the basic resolution applied by the microcomputer. It includes error compensating portion for correcting the error start point and the end point error due to mismatch.

Accordingly, the present invention can be expected to provide an effect of providing more stable measurement and precise control in various fields requiring precise pressure measurement.

Pressure sensor, frequency counter, resolution, pressure measuring device, time difference

Description

Ultra Precision Pressure Measuring Equipment {PRECISION PRESSURE MEASURING APPARATUS}

The present invention relates to an ultra-precision pressure measuring device, and more particularly, to measure the time difference between the reciprocal characteristic and the synchronization mismatch in a conventional frequency measuring method and to compensate for the error, which is output from the frequency output pressure sensor. The present invention relates to a pressure measuring device that extends resolution and improves precision for frequency measurement.

In general, a pressure measuring device measures the pressure of a fluid or a gas or a pressure applied to a measurement object. The pressure measuring device detects an output of an element whose electrical characteristics are deformed with respect to pressure, such as a load cell or a pressure sensor, and converts it into pressure data. .

The pressure measuring device is widely used in various fields such as the control of the supply flow rate and supply pressure of various raw materials with high accuracy, and the measurement of the leakage of the pipe from the pressure change amount by detecting the pressure acting on the pipe.

In addition, it is widely used in the fields such as manual pressure calibration system, meteorological observation, flow measurement, precision pressure measurement.

The pressure sensor converts the displacement, deformation, magnetism, thermal conductivity, etc. by external force into electrical signals and outputs them. Mechanical and electronic pressure sensors are mainly used, but semiconductor pressure is provided with miniaturization, high performance, and mass production through the development of semiconductor technology. Sensors are mainly used. The pressure sensor and the pressure measuring device do not cause a problem in the measurement within the error range by generating an offset according to the offset and the durability of use, but there is a problem in that precision measurement is impossible by generating an error as much as the offset value in the precision measurement. .

Therefore, in order to manufacture an ultra-precision pressure measuring device with a standard level or higher, a pressure sensor having a high precision must be applied on the basis, and the ultra-precision pressure measuring device is realized by how precisely and stably the output of the pressure sensor can be detected and measured. Whether or not is determined.

The present invention has been invented to solve the above problems, the object of which is to measure the frequency output from the frequency output pressure sensor by applying the characteristics opposite to the conventional measurement method to expand the resolution for frequency measurement and precision It is to provide an ultra-precision pressure measuring device that improves.

The present invention is to provide an ultra-precision pressure measuring device that compensates for the error by measuring the synchronization mismatch time difference between the gate time and the input frequency, thereby further improving the resolution and precision to provide an accuracy of ± 0.005% or more and a resolution extension of 0.0001% or more. .

Pressure measuring apparatus according to a feature of the present invention for realizing the above object is to rectify the commercial AC power to convert the DC voltage and then supply to the operating power (V1 ~ Vn) required for each load element constituting the pressure measuring device Power supply; A key input unit comprising one or more function keys and adjustment values to select pressure measurement and result analysis, and to select overall operation of the pressure measuring device; An LCD panel, including a backlighting function and a function of adjusting color and brightness, and displaying a pressure measurement result in a graphic, text, or predetermined manner; An analog output unit for connecting an analog expansion device to transmit pressure measurement and analysis results; A communication unit that supports communication methods of RS232, RS485, and IEEE488, and provides pressure measurement and analysis results and transmission and reception of correction data through a communication method supported by connecting an expansion device, an analysis device, a backup device, or a control device; A signal processing unit which applies resolution characteristics provided to the measurement frequency to the pressure sensor to increase resolution and precision, and compensates for an error by calculating a synchronization mismatch time difference between a gate time and an input frequency; It includes a control unit for controlling the general functions of all the modules constituting the pressure measuring device, displaying the results of the pressure measurement and analysis in a set manner through the display unit, and transmits to a device connected to the communication unit or the analog output unit.

The signal processor includes an oscillator for oscillating a reference clock; A frequency counter for countering a frequency applied by the pressure sensor within a basic resolution according to the reference clock applied by the oscillator; A time difference measuring unit for calculating a starting point error "A" and an ending point error "B" for generating a mismatch between a gate time and an input frequency according to a reference clock applied from the oscillator, and then counting frequencies for the difference parts; An F / V conversion unit for converting a frequency exceeding the basic resolution integrated by the time difference measuring unit into a voltage value; An A / D converter converting a voltage value of an analog state applied from the F / V converter into a digital value; A microcomputer for controlling a reference clock oscillation of the oscillator and converting a digital value applied from an A / D converter into a frequency; And an error compensator configured to compare the integration frequency within the basic resolution applied by the frequency counter with the integration frequency for the excess of the basic resolution applied by the microcomputer to correct the start point error and the end point error due to synchronization mismatch.

By the above-described configuration, the present invention provides an ultra-precision pressure measuring apparatus provided with precision and resolution expansion, and thus, the effect of providing more stable measurement and precise control in various fields requiring precise pressure measurement can be expected.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

1 is a block diagram showing the configuration of a pressure measuring device according to an embodiment of the present invention, as shown in the pressure sensor 110, the signal processing unit 120, the controller 130, the display driver 140, the display unit ( 150, an analog output unit 160, and a communication unit 170.

The pressure sensor 110 has a precision of 0.01% or more and a resolution of 0.0001% or more, and is a conventional pressure sensor that outputs information on the pressure to be pressurized at a frequency.

The signal processor 120 increases the resolution and precision by applying a characteristic that is opposite to the frequency applied from the pressure sensor 110, and compensates for the error by calculating a synchronization mismatch time difference between the gate time and the input frequency.

The controller 130 controls the general functions of all the modules constituting the pressure measuring device, controls the pressure measurement results to be displayed through the display unit 150, and the maximum and minimum values are changed with respect to the change value of the measured pressure. To be displayed at the same time.

The controller 130 includes a memory for storing data, stores information such as measured pressure information, resolution, and pressure unit, and stores up to 99 measurement information.

In addition, the controller 130 allows the pressure measurement result to be transmitted to an expansion device, an analysis device, or a backup device that is connected to the communication method set in the communication unit 170, information provided by the adjusting device connected to the communication unit 130 Correct the error or upgrade the set function.

The display driver 140 drives the display unit 150 according to the control signal applied from the controller 130 so that the pressure measurement result can be displayed.

The display unit 150 is formed of an LCD panel, and includes a back lighting function and a function of adjusting color and brightness, and displays the pressure measurement result in a graphic, text, or various manners set.

The analog output unit 160, for example, 4 to 20mA, 0 to 5V / 0 to 10V (Spec) to connect the other analog expansion device.

The communication unit 170 supports communication methods of RS232, RS485, and IEEE488, and pressure information and analysis results measured through communication methods supported by connecting an expansion device, an analysis device, a backup device, or an adjusting device, and other necessary information. Provides the sending and receiving of information.

Key input unit 180 is composed of a variety of function keys and adjustment keys that can be executed by simply and simply operating pressure measurement and result analysis.

The power supply unit 190 rectifies the commercially available power of 220V, converts it to a DC voltage, and then supplies it to the operating power (V1 to Vn) required for each load element constituting the pressure measuring device.

FIG. 2 is a block diagram illustrating a detailed configuration of the signal processor 120 shown in FIG. 1. As illustrated, the frequency counter 121, the time difference measurer 122, the F / V converter 123, and A are shown. The / D converter 124 includes a microcomputer 125, an oscillator 126, and an error compensator 127.

The frequency counter 121 counts and integrates the frequency applied by the pressure sensor 110 within the basic resolution according to the reference clock of 10 MHz applied by the oscillator 126 within a basic resolution.

The time difference measuring unit 122 calculates a start point error "A" and an end point error "B" which generate a mismatch between the gate time and the input frequency according to the reference clock of 10 MHz applied by the oscillator 126, and then the frequency of the difference portion. To be integrated.

The F / V converter 123 converts a frequency exceeding the basic resolution accumulated by the time difference measurer 122 into a voltage value and outputs the converted voltage.

The A / D converter 124 converts the voltage value of the analog state applied from the F / V converter 123 into a digital value.

The microcomputer 125 controls the reference clock oscillation of the oscillator 126 and converts the digital value applied from the A / D converter 124 into a frequency.

The oscillator 126 oscillates a reference clock of 10 MHz under the control of the microcomputer 125 so that the frequency counter can be executed.

The error compensator 127 calculates a start point error and an end point error due to synchronization mismatch by comparing an integration frequency within the basic resolution applied by the frequency counter 121 with an integration frequency for the excess of the basic resolution applied by the microcomputer 125. Then compensate for the error in the measured frequency.

Referring to the operation of the pressure measuring device according to the present invention including the function as described above are as follows.

There are two main methods of measuring the frequency applied from the frequency output type pressure sensor, one of which is a method of measuring and calculating one cycle time of the frequency under measurement, and the other is a specific time (reference time). It is a method to count and measure the pulse inside.

Both of the above methods rely on the reference clock. The former method has a characteristic in which the resolution is increased when the frequency is low, and the resolution is decreased when the frequency is high, as shown in "a" of FIG. The higher the frequency, the higher the resolution. The lower the frequency, the lower the resolution.

The present invention is to secure the basic resolution and precision of the frequency measurement to the maximum based on the reference clock using the characteristics opposite to the characteristics of the "a" and "b" and then to enlarge the resolution and precision through the time difference measurement " c ".

The operation thereof is described in detail as follows.

When the power of the pressure measuring device is turned on, the power supply unit 109 rectifies and down the input AC 220V power and supplies each module constituting the pressure measuring device as operating power to enter the standby state.

When the frequency is applied to the signal processor 120 from the pressure sensor 110 of the frequency output type while the pressure measuring device maintains the standby state, the frequency counter 121 constituting the signal processor 120 is oscillated from the oscillator 126. According to the reference clock of 10MHz provided, the frequency applied from the pressure sensor 110 is counted and integrated within the basic resolution, and then applied to the error correction unit 127.

In order to accurately measure the frequency applied from the pressure sensor 110, knowing exactly the "C" time in the relationship between the gate time and the input frequency shown in Figure 4, and knowing the exact number of counters of the frequency input during the "C" time It can be measured.

In practice, however, as shown in FIG. 4, the synchronization between the gate time and the input frequency does not coincide, so that an error of the difference occurs.

Therefore, the starting point error "A" and the ending point error "B" should be obtained and compensated for.

To this end, the gate time is calculated through Equation 1 below.

Gate time = count / reference clock

In addition, since the resolution is determined according to the frequency of the reference clock, the frequency depends on the reference clock.

Therefore, the frequency is calculated through Equation 2 below.

Frequency = Input Counter / Gate Time

By applying the above Equations 1 and 2, it is possible to obtain the starting point error "A" and the ending point error "B" for the mismatch between the gate time and the input frequency in FIG.

Therefore, the time difference measuring unit 122 calculates the starting point error "A" and the ending point error "B" by applying the above-described method according to the 10 MHz reference clock applied from the oscillator 126, and then the difference portion, that is, the basic The frequency exceeding the resolution is integrated and applied to the F / V converter 123.

The F / V converter 123 converts a frequency exceeding the basic resolution accumulated by the time difference measurer 122 into a voltage value, and then applies the F / V converter 123 to digitally convert the voltage value of the analog state. Convert to a value.

The microcomputer 125 converts the digital value applied from the A / D converter 124 into a frequency and then applies it to the error compensator 127.

Accordingly, the error compensator 127 compensates the starting point error and the ending point error due to the synchronization mismatch by comparing the frequency of the deviation within the basic resolution applied by the frequency counter 121 with the frequency of the deviation applied by the microcomputer 125. .

For example, in the case of measuring 170Khz set as the output frequency of the pressure sensor 110 by applying a reference clock of 10Mhz outputted from the oscillator 126, when the gate time is set to 1 second, 170.000Khz of the frequency counter 121 is used. You get resolution.

And, if the gate time is set to 10 seconds, the resolution of 170.0000Khz is obtained through the frequency counter 121, and if it is set to 0.1 seconds, the resolution of 170.00Khz is obtained through the frequency counter 121.

In addition, when converting the 170Khz set as the output frequency of the pressure sensor 110 through the time difference measuring unit 122 to time is 5.88235294 ,, of which the accuracy is obtained up to 100 kHz as a reference clock of 10Mhz, 5.8 ㎲ (172.413 Khz), 5.9 ㎲ (169.491 Khz).

As described above, when the error correction is completed and then applied to the control unit 130 for the frequency input to the pressure sensor 110 by the signal processing unit 120, the control unit 130 displays the result of the pressure measurement according to the set display method. The control unit 140 controls the display unit 150 to display characters, graphics, or a specific method through the display unit 150.

In addition, the pressure measurement results are transmitted to an expansion device, an analysis device, or a backup device connected to the communication unit 170 by a communication method such as RS232, RS485, IEEE488.

As a result of applying the above-described pressure measuring device according to the present invention, as shown in FIG. 5, a measurement result having an input-output relationship such as (A) provides an accurate measurement having an input-output relationship such as (B). do.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It is included in the scope of rights.

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

FIG. 2 is a block diagram illustrating a detailed configuration of a signal processor in FIG. 1.

3 is a graph showing the relationship between resolution and frequency in the pressure measurement according to an embodiment of the present invention.

4 is a diagram illustrating a mismatch relationship between gate time and frequency in pressure measurement according to an exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

110: pressure sensor 120: signal processing unit

130: control unit 140: display driving unit

150: display unit 160: analog output unit

170: communication unit

Claims (2)

Rectifying commercial AC power, converting it into DC voltage, and then supplying power to each load element as operating power, one or more function keys and adjustment keys, and a key input to select overall operation, and a display to display pressure measurement results in a set manner. A pressure measuring device including an analog output unit for connecting an analog expansion device, and a communication unit for transmitting and receiving pressure measurement and analysis results and correction data using any one of RS232, RS485, and IEEE488 communication methods with an external device connected thereto. To A signal processor to compensate for an error by applying a resolution of a reciprocal feature that rises or falls according to a frequency with respect to a measurement frequency provided by a pressure sensor, and calculates a synchronization mismatch time difference between a gate time and an input frequency; Pressure measurement further comprising a control unit for controlling the general functions of all the modules constituting the pressure measuring device, displaying the pressure measurement and analysis results in a set manner through the display unit, and transmits to a device connected to the communication unit or analog output unit. Device. The method of claim 1, The signal processor includes an oscillator for oscillating a reference clock; A frequency counter for countering a frequency applied by the pressure sensor within a basic resolution according to the reference clock applied by the oscillator; A time difference measuring unit for calculating a start point error and an end point error for generating a mismatch between a gate time and an input frequency according to a reference clock applied from the oscillator, and then counting frequencies for the difference parts; An F / V conversion unit for converting a frequency exceeding the basic resolution integrated by the time difference measuring unit into a voltage value; An A / D converter converting a voltage value of an analog state applied from the F / V converter into a digital value; A microcomputer for controlling a reference clock oscillation of the oscillator and converting a digital value applied from an A / D converter into a frequency; And an error compensator configured to compare the integration frequency within the basic resolution applied by the frequency counter with the integration frequency for the excess of the basic resolution applied by the microcomputer to correct the start point error and the end point error due to synchronization mismatch.

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