JP2005164406A - Digital pressure gauge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital pressure gauge in which a self-control feature and an adjustment history management feature are imparted to have pressure characteristics suited for a standard owned by a user as well as to reduce adjustment costs and prevent quality deterioration. <P>SOLUTION: The digital pressure gauge to measure pressure based on output signals of a pressure sensor and a preset correction factor comprises a correction factor calculation means which calculates the correction factor based on output signals when predetermined standard pressure is applied to the pressure sensor and stores the correction factor into a storage means, and a history creation means which creates history information on the correction factor and stores the information into the storage means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a digital pressure gauge, and more particularly to an improvement for performing high-quality pressure measurement by a self-adjusting function and a history management function.

  In recent years, research on intercomparison between countries is progressing towards international recognition of pressure standards. A digital pressure gauge is used as a transfer for comparative tests for the purpose of improving work efficiency of research.

In Japan, pressure gauges other than conventional weight-type pressure balances are also certified by JCSS (Measuring Law Traceability System), and digital pressure gauges are used for pressure measurements that require high accuracy, and are used at the product's ability level. Has been. In the future, demand for a digital pressure gauge with higher accuracy is expected.

  In addition, there is a service for high-precision products in remote locations such as overseas. If pressure adjustment is required at a remote location, it must be returned to the manufacturer, which is time consuming and expensive. Here, there are the following prior art documents related to the conventional digital pressure gauge (for example, refer to Patent Document 1).

JP 2001-66210 A

FIG. 3 is an explanatory view showing an adjustment (calibration) system of a conventional digital pressure gauge.
In FIG. 3, the standard digital pressure gauge 1a or the weight-type pressure balance 1b is a secondary standard. The secondary standard 1 is adjusted (valued) based on the pressure standard (primary standard) supplied from the National Standards Bureau.

  Zero adjustment, span adjustment, linearity correction, temperature calibration, and the like are performed on the digital pressure gauge to be adjusted 3 so as to have the same pressure characteristics as the secondary standard device 1. The adjustment is performed by communication with an external personal computer 4 (hereinafter referred to as a PC).

  Specifically, a predetermined pressure is measured by the standard digital pressure gauge 1a, a correction coefficient is calculated by the PC 4 so that the display value when the same pressure is measured by the adjustment target 3 is the same, and this correction coefficient is calculated. Input to the adjustment target 3 by communication.

  Alternatively, a known pressure is output to the adjustment target 3 by the weight-type pressure balance 1b, a correction coefficient is calculated by the PC 4 so that the display of the adjustment target is equal to the known pressure value, and this correction coefficient is adjusted by communication. Type in 3.

FIG. 4 is a block diagram showing an example of a conventional digital pressure gauge.
In FIG. 4, the pressure sensor 5 converts the input pressure into an electrical signal. For example, the pressure is converted into an electric signal having a natural frequency by using a silicon resonant pressure sensor. The control means 6 is realized by a CPU (Central Processing Unit) and a program, controls the entire digital pressure gauge, counts the frequency of the signal output from the pressure sensor 5, and calculates using a preset correction coefficient. Then, the pressure is calculated, and the pressure value is displayed on the display means 7 such as a liquid crystal panel or CRT.

The input unit 8 includes a key panel and a touch panel, and receives an operation from the user and outputs an operation signal to the control unit 6. The communication means 9 exchanges data with the PC 4, and the control means 6 takes the correction coefficient calculated by the PC 4 through the communication means 9 into the digital pressure and stores it in the storage means 10 which is a memory. In the pressure measurement, the pressure is calculated using this correction coefficient.

The internal processing related to the calculation of the correction coefficient is as follows.
An arbitrary reference pressure is input to the pressure sensor, and the frequency signal output from the pressure sensor is measured. This process is performed at an arbitrary temperature point, and a correction coefficient for each pressure sensor is obtained by a pressure correction formula (determinant) based on the data. As a result, the pressure value is obtained from the frequency signal of the input pressure and the correction coefficient of each sensor.
Among the correction coefficients, there are correction terms that improve zero, span, and linearity under a certain temperature environment (for example, 23 ° C.), and the pressure characteristics can be changed by fine adjustment.

However, the adjustment of the digital pressure gauge is generally performed by calibrating the secondary standard using the primary standard and calibrating the product digital pressure gauge using the secondary standard. Yes.
During adjustment and inspection, since absolute values of a certain width are used, the absolute error of the product on the lower side inevitably increases. When correcting measurement errors, the digital pressure gauge does not have a function to calculate the correction coefficient, so the operator calculates the measured value by correcting the displayed value of the product based on the pressure value of the standard device owned by the user. This is the current situation.

For example, when pressure adjustment is required in a remote place such as overseas, it is not possible to adjust the pressure locally, and it is necessary to return it to the manufacturer. This incurs transportation time and costs.
On the other hand, if the user can perform adjustment work, it does not necessarily have an environment or equipment that can be priced with high accuracy, and there is a problem that quality deteriorates due to unnecessary adjustment. .

The present invention is intended to solve the problems of such a conventional digital pressure gauge. A self-adjustment function and an adjustment history management function are added to the digital pressure gauge, in accordance with a standard device owned by the user. The purpose is to realize a digital pressure gauge that can reduce the adjustment cost and prevent the deterioration of quality caused by adjustment.

  The present invention is a digital pressure gauge configured as follows.

(1) In a digital pressure gauge that measures pressure based on an output signal of a pressure sensor and a preset correction coefficient,
Correction coefficient calculation means for calculating the correction coefficient based on an output signal when a predetermined standard pressure is applied to the pressure sensor, and storing the correction coefficient in a storage means;
Creating history information of the correction coefficient and storing history information in the storage means;
A digital pressure gauge characterized by the provision of

(2) The digital pressure gauge according to (1), wherein the initially set correction coefficient and the calculated correction coefficient are distinguished and stored in the storage means.

(3) The digital pressure gauge according to (1), wherein the storage means includes a plurality of memories, and the initially set correction coefficient and the calculated correction coefficient are stored in separate memories. .

(4) The digital pressure gauge according to any one of (1) to (3), wherein the correction coefficient is a coefficient for correcting at least one of zero, span, linearity, static pressure, and ambient temperature. .

(5) The history information is at least one of setting information when adjusting the standard pressure, an adjustment date, and additional information of adjustment pressure measurement data. (1) to (4) A digital pressure gauge according to any one of the above.

The present invention has the following effects.

According to the first, fourth, and fifth aspects of the present invention, by calculating and storing the correction coefficient in the digital pressure gauge, the pressure characteristic according to the standard device owned by the user can be obtained.
In addition, since the user can adjust the pressure at a remote location, the time and cost associated with the adjustment can be reduced.
Furthermore, no PC is required for calculating the correction coefficient, and the work can be simplified.
In addition, by performing history management at the time of adjustment, adjustment under the same condition or adjustment under different conditions can be performed.

  According to the second and third aspects of the invention, since the initial correction coefficient and the new correction coefficient are stored separately in the memory, the initial state is restored even when inappropriate adjustment is performed. be able to. Therefore, it is possible to realize a digital pressure gauge that prevents quality deterioration.

FIG. 1 is a block diagram showing an embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the thing similar to the previous figure, and the description of the part is abbreviate | omitted.
In FIG. 1, standard pressure (eg, pressure from a weight-type pressure balance) at any pressure point in the pressure sensor is supplied to the pressure sensor.

The control means 6a is realized by a CPU and a program, controls the entire digital pressure gauge, counts the frequency of the signal output from the pressure sensor 5, and calculates the pressure by calculation using a preset correction coefficient. Then, the pressure value is displayed on the display means 7 such as a liquid crystal panel or a CRT. At this time, the setting of the sampling time, moving average time, and measurement time for obtaining a stable pressure, which are conditions related to measurement, is input from the input means 8 in advance. Thereafter, the same operation is repeated while changing the supply pressure, and adjustment pressure measurement data necessary for pressure correction calculation is collected.

The correction coefficient calculation means 61 is provided in the control means 6a, calculates a correction coefficient based on the collected adjustment pressure measurement data, and writes it in the storage means 10 which is a memory. However, the correction coefficient (initial setting value) at the time of shipment is differentiated, and another area of the same memory or a plurality of memories are provided and written in different memories, and shipped by operation from the operation means 8 as necessary. It will be possible to return to the pressure characteristics of the hour.

The history creation means 62 is provided in the control means 6a. When a new adjustment (calculation of correction coefficient) is performed, the date of adjustment, additional information of pressure measurement data for adjustment (pressure adjustment point, pressure change amount during adjustment, Temperature), device setting conditions (sampling time, number of moving averages, number of samplings, etc.) are stored in the same memory of the storage means 10 or in another memory provided separately.

FIG. 2 is a flowchart showing an example of the process of the self-adjusting function in the present invention.
Each step will be described in the order shown in FIG.

(S1) The adjustment mode is entered by inputting the password set by the user by key operation on the front panel. (The PIN is intended to allow adjustment by a limited operator.)
(S2) Select zero, span adjustment, linearity adjustment, and other adjustments.
(S3) When adjusting zero and span, input standard pressures of 0% and 100% of the measurement range are applied, and when adjusting linearity, an arbitrary intermediate pressure is applied, so the input standard pressure is set.
(S4) A standard pressure corresponding to 0% and 100% of the range is input to the digital pressure gauge using a weight-type pressure balance or the like.

(S5) Data collection is automatically started and ended by key operation on the front key panel. At this time, the following conditions are set in advance.
・ Sampling time ・ Number of moving averages ・ Number of sampling (or measurement time)

(S6) The normality / abnormality of the collected data is determined. Specifically, calculate the following values and confirm that they are within the rules.
・ Dispersion of collected data (standard deviation)
・ Change in pressure during measurement (pressure drop)
・ Standard pressure input due to incorrect operation (difference from set input standard pressure)
If the determination result is NG, the process of step (S5) is performed, and if it is OK, the process of step (S7) is performed.

(S7) It is determined whether the collection of the adjustment pressure measurement data necessary for calculating the correction coefficient is completed. If it is NG, the process of step (S3) is performed, and if OK, the process of step (S8) is performed. I do.
(S8) A correction coefficient is calculated using the collected adjustment pressure measurement data.
(S9) The calculated correction coefficient is written in the memory.

In addition, although a present Example is the content corresponding to a zero, a span, and a linearity adjustment function, in addition to that, the digital pressure gauge has various correction functions. For example, there is static pressure correction in differential pressure measurement. Specifically, the same pressure is applied to the Low and High side input ports, and numerical calculation is performed based on a signal from the pressure sensor, thereby reducing the influence of static pressure.

Further, pressure measurement data in a certain set temperature range is collected, and temperature characteristics are measured from this. Based on this, a correction coefficient for flattening the pressure measurement characteristic in a certain temperature range is obtained with respect to the measurement temperature of the temperature sensor built in the digital pressure gauge. As a result, a pressure gauge that is not affected by an ambient temperature range in which a pressure measurement value is present can be obtained. This is called temperature calibration. These can also be applied as a similar self-adjusting function.

  Further, it is considered that the present invention can be applied not only to a digital pressure gauge but also to a high-precision measuring instrument having a certain adjustment parameter and requiring a price from a certain standard device.

As described above, by adjusting the zero, span, and linearity, the digital pressure gauge can be made to have a pressure characteristic that conforms to the standard device owned by the user.
In addition, since the user can adjust the pressure gauge at a remote location, the time and cost associated with the adjustment can be reduced.
Furthermore, since a series of adjustment pressure measurement data collection and complicated correction coefficient calculation processing can be performed only by panel operation, a PC is not required, and the work can be simplified.

In addition, since individual digital pressure gauges can be set to characteristics according to the user's wishes, differentiation from other digital pressure gauges is possible.
Then, by distinguishing the correction coefficient at the time of shipment from the correction coefficient obtained by the adjustment by the user, the state at the time of shipment can be restored from an inappropriate user adjustment, so that the quality boundary for the adjustment can be clarified.

  The present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

It is the block diagram which showed one Example of this invention. It is the flowchart which showed an example of the process of the self adjustment function in this invention. It is explanatory drawing which showed the adjustment (calibration) system of the conventional digital pressure gauge. It is the block diagram which showed an example of the conventional digital pressure gauge.

Explanation of symbols

5 Pressure sensor 6a Control means 7 Display means 8 Input means 9 Communication means 10 Storage means 61 Correction coefficient calculation means 62 History creation means

Claims (5)

In a digital pressure gauge that measures pressure based on an output signal of a pressure sensor and a preset correction coefficient,
Correction coefficient calculation means for calculating the correction coefficient based on an output signal when a predetermined standard pressure is applied to the pressure sensor, and storing the correction coefficient in a storage means;
Creating history information of the correction coefficient and storing history information in the storage means;
A digital pressure gauge characterized by the provision of 2. The digital pressure gauge according to claim 1, wherein the initially set correction coefficient and the calculated correction coefficient are distinguished and stored in the storage means. The digital pressure gauge according to claim 1, wherein the storage unit includes a plurality of memories, and the initially set correction coefficient and the calculated correction coefficient are stored in separate memories. The digital pressure gauge according to any one of claims 1 to 3, wherein the correction coefficient is a coefficient for correcting at least one of zero, span, linearity, static pressure, and ambient temperature. 5. The history information according to claim 1, wherein the history information is at least one of setting conditions, adjustment date, and adjustment pressure measurement data when measuring the standard pressure. Digital pressure gauge as described in.

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