JP2006153623A - Ph meter with automatic erasure determining function of calibration data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pH meter capable of performing multipoint calibration of two or above points without hindrance at the time of calibration due to a standard liquid, capable of also preventing impossibility to get out of a calibration error, more reduced in the number of button operations required in calibration than before and simple in calibration operation. <P>SOLUTION: The pH meter with an automatic erasure judging function of calibration data has a function for automatically determining whether the previous calibration data is erased on the basis of the date of the previous calibration or the elapse time of the previous calibration when calibration is performed and is constituted so as to automatically perform respective processings by determining a process A for superscribing the calibration data of this time on the previous calibration data, a process (C) for erasing the previous calibration data to employ the calibration data of the time and a process (B) for displaying the intermediate notice message thereof. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pH meter for measuring the hydrogen ion concentration of a sample solution, and more particularly to a pH meter that can automatically determine whether or not to erase previous calibration data during calibration.

  In a normal pH meter, it is necessary to calibrate with a standard solution before measuring a sample solution. In a pH meter equipped with a recent arithmetic processing unit (CPU), calibration data obtained by calibration with a standard solution is stored in a memory, and when a sample solution is measured with a pH sensor (glass electrode and comparison electrode), The CPU computes the input value sent from the pH sensor to obtain measurement data, and displays it on the display unit or prints it and outputs it.

  The number of calibration points when calibrating with a standard solution is generally 1 to 5 points. That is, if rough measurement is acceptable, one-point calibration at the zero point using pH 7 may be performed, but for example, two-point calibration of zero point calibration at pH 7 and span calibration at pH 4 or pH 9 is usually performed. Yes. When more accurate measurement is required, multipoint calibration of three or more points such as zero point calibration at pH 7 and span calibration at pH 4 and pH 9 is performed. In the calibration of two or more points, a slope (tilt) is obtained from the potential difference between each point. Further, the frequency or cycle of calibration with the standard solution varies depending on what is measured as the sample solution, what purpose is measured, and the like.

  When actually calibrating, the previous calibration data is usually erased manually. This is because, if the previous calibration data is left, it may not be possible to escape from the calibration error when a calibration error occurs. For example, if a calibration operation is performed without erasing the previous calibration data, the current calibration data is overwritten with the previous calibration data, but the previous calibration data is old and has a zero point (asymmetric potential) or slope (slope). If the zero point or slope is calculated using the previous calibration data and the current calibration data, for example, when there is a large change, the situation may not match and the calibration error may not be escaped.

  To avoid this problem, set the calibration data so that the previous calibration data is automatically deleted when calibration is performed with the standard solution after operating the calibration button. It is considered the easiest to keep. However, this method of automatically erasing the previous calibration data has a serious drawback that two-point calibration and multi-point calibration cannot be performed. That is, when considering a two-point calibration in which pH 4 is calibrated after pH 7 is calibrated, if pH 4 is later calibrated, the previously performed calibration data for pH 7 is also deleted.

  Another method is to set up a calibration mode in advance, enter the calibration mode by operating buttons, etc., then automatically erase the previous calibration data, and then calibrate the required number of points in the calibration mode. When calibration is completed, there is a method of returning from the calibration mode to the measurement mode by operating a button or the like. There is also a method in which the number of calibration points is set in advance by operating a button in the calibration mode, and when the calibration of the set number of points is completed, the mode is automatically returned to the measurement mode. However, both methods have a problem that the calibration operation becomes complicated because the number of times of operating buttons and the like increases.

Although not related to the pH meter, Japanese Patent Application Laid-Open No. 9-15139 discloses a method for configuring a gas analyzer that is updated when the calibration coefficient calculated in the calibration is within a preset normal calibration range. There has been proposed a method for indicating that the calibration is impossible when it is in the impossible range. Japanese Patent Laid-Open No. 2000-275207 discloses a method of measuring a specific sample using a calibration curve updated at the previous calibration in order to suppress the consumption of a reagent used for calibration in an electrolyte concentration measurement device. Based on this, a method for determining whether or not to perform calibration this time is described.
Japanese Patent Laid-Open No. 9-15139 JP 2000-275207 A

  In view of the above-described conventional circumstances, the present invention can not only perform multi-point calibration of two or more points without any trouble when calibrating with a standard solution, but also prevent a calibration error from being lost. An object of the present invention is to provide a pH meter that requires a small number of button operations and can be easily calibrated.

  In order to achieve the above object, the pH meter provided by the present invention automatically determines whether or not to erase the previous calibration data based on the date of the previous calibration or the elapsed time since the previous calibration when calibration is performed. It has the function to judge to. Further, the pH meter of the present invention described above is a process of erasing the previous calibration data and adopting the current calibration data according to the determination, or overwriting the current calibration data without erasing the previous calibration data. The process which performs is performed.

  In the pH meter of the present invention, in addition to the two processes based on the determination, a process for obtaining an instruction whether to erase the previous calibration data or to overwrite the current calibration data without erasing the calibration data may be performed. it can. Also, the previous calibration data that is erased during the calibration can be automatically stored as a calibration history.

  In the pH meter of the present invention, when the calibration data is overwritten, the current calibration data is compared with the previous calibration data to automatically determine whether the calibration data is within a preset appropriate range. It preferably has a function. This pH meter performs the process of overwriting the previous calibration data with the current calibration data when the current calibration data is within the appropriate range, and overwriting or recalibrating when the calibration data is outside the appropriate range. The process which calculates | requires is performed.

  According to the pH meter with the automatic erasure judgment function of the calibration data of the present invention, whether or not the previous calibration data is erased when calibrating with the standard solution is based on the date of the previous calibration or the elapsed time from the previous calibration. In addition, it is possible to automatically determine whether or not the current calibration data is within an appropriate range as compared with the previous calibration data. Therefore, even when the zero point (asymmetric potential) or slope (tilt) changes greatly with respect to the previous calibration data, the occurrence of a calibration error is eliminated and the calibration error cannot be escaped.

  In addition, it is possible to perform not only one-point calibration but also multi-point calibration of two or more points without any trouble even if the number of calibration points is not set in advance as usual. In comparison, the number of button operations required for calibration is reduced, and the calibration operation can be performed easily and conveniently.

  In general, in the calibration of a pH meter, the longer the time interval between calibrations, the greater the change in the zero point (asymmetric potential) and slope (slope) of the previous and current calibration data. If calibration is performed without erasing the previous calibration data, the frequency of occurrence of calibration errors increases. Therefore, the pH meter of the present invention has a function of automatically determining whether or not to erase the previous calibration data based on the date of the previous calibration or the elapsed time since the previous calibration. The specific determination criteria can be set in advance in the pH meter, and can be arbitrarily set later.

  For example, when the date of the previous calibration is used as a reference, that is, when the criterion for erasing the calibration data is one point, whether the current calibration is the same date as the previous calibration date or the date of the previous calibration date The time is not a problem. Specifically, for example, when the date of the previous calibration is the same as the date of the current calibration, the date of the previous calibration data stored in the CPU is today (this time Calibration date), since the same date of judgment criteria is satisfied, the previous calibration data is not erased and the current calibration data is overwritten on it. However, if the date of the previous calibration data is yesterday or earlier, it does not satisfy the same day of judgment criteria, so the previous calibration data is deleted and the current calibration data is newly stored.

  FIG. 1 shows a specific example in the case where the above-mentioned calibration date is used as a reference and the judgment standard for deleting calibration data is one point. As shown in FIG. 1, when the judgment standard for erasing the calibration data is set to 0:00 am today (September 13), the previous calibration data is dated before 0:00 am on September 13 ( b) is erased and the current calibration data is newly stored. In addition, the previous calibration data whose date is today (a) is not deleted, and new calibration data is overwritten on the previous calibration data. As a means for entering the calibration, it is sufficient to use a calibration button or a calibration mode button as usual. Further, even when performing multi-point calibration of two or more points, it is not necessary to set the number of calibration points by button operation or the like as in the prior art.

  Similarly, even when the criterion is one point, the elapsed time from the previous calibration can also be used as a reference. In this case, the calibration data indicates whether or not the current calibration is within a predetermined time from the previous calibration. Use the criteria for erasure. Specifically, for example, when 24 hours is used as the criterion for the elapsed time from the previous calibration, if the current calibration is within 24 hours from the previous calibration data stored in the CPU, for example, the date is Even on the next day of the previous calibration date, the previous calibration data is not erased and the current calibration data is overwritten. However, when the current calibration exceeds 24 hours from the time of the previous calibration data, the previous calibration data is deleted and the current calibration data is newly stored.

  Further, as a more detailed determination with respect to the determination at one point based on the date of the previous calibration or the elapsed time from the previous calibration, the determination criterion for deleting the calibration data can be set at two points. Specifically, when the date of the previous calibration is used as a reference, for example, two points are that the current calibration is the same date as the previous calibration date and that it is within 7 days from the previous calibration date. Judgment criteria. Then, these two points determine the current calibration date. If the date is the same as the previous calibration date, the previous calibration data is overwritten with the current calibration data without being erased. The process of erasing the calibration data and memorizing the current calibration data is adopted, and if it falls within the next day to the 7th day, either the previous calibration data is erased or it is overwritten without being erased. It is set to perform processing for requesting whether to do.

  FIG. 2 shows a specific example in the case where the above-mentioned calibration date is used as a reference, and there are two criteria for erasing calibration data, and FIG. 3 shows a flowchart thereof. When the criteria for deleting calibration data are set to 1 point at 0:00 am today (September 13) and 2 points at 0:00 am one week before (September 6) The previous calibration data whose date is today (A) is not deleted, and new calibration data is overwritten. Further, the previous calibration data (C) whose date is before 0:00 am on September 6 is deleted, and new calibration data is stored. However, for the case where the previous calibration data is between September 6, 0:00 am and September 13, 0:00 am (B), for example, “Would you like to overwrite the calibration data?” A message can be displayed and the operator can be asked to select whether to overwrite.

  Regarding the warning message in the case of (B) above, for example, a method for obtaining an instruction whether to erase the previous calibration data or to overwrite without erasing, display a simple message or a symbol for requesting the instruction on the display unit, or It is possible to use a method of alerting and notifying. In particular, a display using a graphic LCD or the like can output a message in characters, so that, for example, not only displays each process of automatic erasure or overwriting, but also a character that requests an instruction for erasure or overwriting. Messages can be displayed easily. In addition, it is possible to set in advance which one of the above-described one-point or two-point judgment criteria is adopted, but it is also possible to arbitrarily set or reset later. When an error occurs during the calibration operation described above or when the calibration operation is interrupted, the erase or overwrite of the calibration data is canceled and the original calibration data remains.

  The calibration operation and how the calibration data is handled according to the present invention will be described with reference to specific examples shown in FIGS. FIG. 4 shows a state where calibration has never been performed, and no data is stored in the memory areas 1 to 5 for calibration data. FIG. 5 shows a state in which calibration is performed for the first time. For example, in the case of two-point calibration, calibration data of pH 7 is stored in the memory area 1 and pH 4 is stored in the memory area 2, and an arithmetic expression is created. At this time, by automatically recognizing the standard solution, pH 7 and pH 4 are determined as different standard solutions, and the calibration data of pH 7 and pH 4 are stored in separate memory areas. Therefore, if the criterion for deleting calibration data is set at the boundary between today and yesterday as in FIG. 1, if pH 7 and pH 4 are calibrated today, pH 7 is calibrated after pH 7 is calibrated. However, the pH 7 data is not overwritten with the pH 4 data.

  The state of FIG. 6 is a case where a three-point calibration of pH 7, pH 4, and pH 9 is performed after several days from the state of FIG. When the criterion for erasing calibration data is set at the boundary between today and yesterday as shown in FIG. 1, the previous calibration data stored in the state of FIG. 5 is erased, and the pH 7, pH 4, and pH 9 performed today are deleted. The new calibration data is stored in the memory areas 1 to 3. In this case as well, if three-point calibration is performed today, the standard solutions are stored separately and reflected in the calculation formula regardless of before and after that.

  The state of FIG. 7 is a case where pH 7 is further calibrated independently on the same day as the state of FIG. When the criterion for erasing the calibration data is set at the boundary between today and yesterday as shown in FIG. 1, the new pH 7 calibration data is overwritten on the previous pH 7 data in the memory area 1, but pH 4 and pH 9 The calibration data remains in the memory areas 2 and 3 without being erased. The arithmetic expression in this case is an arithmetic expression reflecting the new calibration data of pH7 and the previous calibration data of pH4 and pH9.

  The state of FIG. 8 is a case where calibration of pH 7 is carried out independently after several days from the state of FIG. If the criterion for deleting calibration data is set to the boundary between today and yesterday as shown in FIG. 1, all previous calibration data of pH 7, pH 4, and pH 9 are erased from the memory areas 1 to 3, and the new calibration performed today Only calibration data of pH 7 is stored in the memory area 1. That is, only one point at pH 7 is performed. Moreover, the state of FIG. 9 is a case where calibration of pH 4 is carried out independently on the same day as the state of FIG. When the criterion for erasing the calibration data is set at the boundary between today and yesterday as shown in FIG. 1, the new calibration data of pH 4 performed today is stored in the memory area 2. Therefore, the two-point calibration of pH 7 and pH 4 is performed.

  As described above, it is preferable that the calibration data erased by the automatic determination is automatically stored in the CPU memory as a calibration history. Whether to automatically store the calibration history may be set in advance, or may be set later. The timing to store the calibration data to be erased as a history can be, for example, when a new calibration is performed. Further, in order to store the calibration history, it is desirable to provide a memory for storing calibration history in the memory of the CPU separately from the memory for storing calibration data. In the conventional pH meter, it was possible to store the history of calibration data, but each time a complicated button operation was required, and what was automatically stored when erasing calibration data not exist.

  In the above-described pH meter of the present invention, the previous calibration data is old in time, and therefore it is set when the zero point (asymmetric potential) and the slope (slope) change seem to be large. Since it is automatically erased based on the judgment criteria, it is possible to prevent the occurrence of a calibration error. Conversely, if the current calibration is the same as or close to the date of the previous calibration, or if the elapsed time since the previous calibration is short, the current calibration data is zero (asymmetric potential) with respect to the previous calibration data. On the premise that the slope and the slope (tilt) are appropriate, the process of overwriting the current calibration data with the previous calibration data is automatically performed.

  Usually, the calibration data incorporates the electromotive force of the standard solution, but the judgment of the electrode state is seen by the asymmetry potential and the slope. The asymmetric potential is an electromotive force in a pH 7 standard solution, and it is usually desirable to use in the range of + 8 ± 30 mV. The slope is the slope of the potential difference between different types of standard solutions. Theoretically, the slope is 59.15 mV / 1 pH (25 ° C.), but the slope gradually decreases due to deterioration over time or dirt. Since it is usually desirable to perform calibration every day, if it is normal, it will not deviate significantly compared to the past calibration data that is very close.

  However, even if the current calibration is the same as or close to the date of the previous calibration, or the elapsed time since the previous calibration is short, it is extremely special, for example, a glass electrode that is a sensor unit or a comparison. If the electrode is left dirty, the glass electrode or the reference electrode is damaged for some reason, or the liquid junction is clogged, the current calibration data will be compared to the previous calibration data. The zero point (asymmetric potential) and slope (slope) may change greatly. In such a case, based on the date of the previous calibration or the elapsed time since the previous calibration, it is automatically determined that the previous calibration data will not be deleted, and if this calibration data is overwritten, a calibration error may occur. .

  In order to avoid calibration errors in such special cases, improve the accuracy of automatic determination in the pH meter of the present invention, and further notify the presence of any abnormality, the current calibration data is overwritten on the previous calibration data. It is preferable to set so as to issue a caution message. That is, as shown in the flowchart of FIG. 10, the current calibration data determined to be overwritten is compared with the previous calibration data, and is within the preset appropriate range (A1) or out of the proper range (A2). It is preferable to provide a function for automatically determining Specific examples of the above appropriate range include, for example, the zero point (asymmetric potential) with an electromotive force of a pH 7 standard solution within ± 10 mV of the previous calibration data, and a slope (inclination) in multipoint calibration of two or more points ) Is set so that it is within ± 10% of the previous calibration data depending on the potential difference of each standard solution. In addition, about the reference | standard of this appropriate range, although it can also set to a pH meter previously, it is also possible to set arbitrarily or to reset afterwards.

  If it is determined that the current calibration data is within the appropriate range (A1), processing for overwriting the previous calibration data with the current calibration data is performed. On the other hand, if it is determined that it is out of the proper range (A2), a process for obtaining an instruction to issue an caution message and overwrite or recalibrate is performed. When instructions for overwriting or recalibration are requested by a caution message, there are many cases where abnormalities such as dirt or damage to the glass electrode or reference electrode or clogging of the liquid junction occur. It is desirable to perform calibration again after inspection. In this case, the method for issuing a caution message may be a method of displaying on a pH meter or emitting a caution sound, as in the case of FIG.

This is a specific example in the case where the date of the previous calibration is used as a reference and the criterion for deleting the calibration data is one point. This is a specific example in the case where the date of the previous calibration is used as a reference and there are two criteria for deleting calibration data. It is a flowchart in the specific example in the case where the date of the last calibration is used as a reference and the determination reference for deleting the calibration data is two points. It is a conceptual diagram which shows the memory area of the calibration data in the state where calibration is not performed. It is a conceptual diagram which shows the memory area of the calibration data in the state which performed calibration for the first time. It is a conceptual diagram which shows the memory area of the calibration data in the state which implemented three-point calibration after several days progress from the state of FIG. It is a conceptual diagram which shows the memory area of the calibration data in the state which implemented one-point calibration of pH7 on the same day as the state of FIG. It is a conceptual diagram which shows the memory area of the calibration data in the state which implemented one-point calibration of pH7 after several days progress from the state of FIG. It is a conceptual diagram which shows the memory area of the calibration data in the state which implemented one-point calibration of pH4 on the same day as the state of FIG. It is a flowchart in the specific example in the case of judging whether calibration data is in the preset appropriate range.

Claims (6)

  A pH meter characterized by having a function of automatically determining whether or not to erase the previous calibration data based on the date of the previous calibration or the elapsed time since the previous calibration when calibration is performed.   The process of erasing the previous calibration data and adopting the current calibration data based on the determination, or performing the process of overwriting with the current calibration data without erasing the previous calibration data. The pH meter according to 1.   The processing for obtaining an instruction whether to erase the previous calibration data or to overwrite the current calibration data without deleting the previous calibration data, in addition to the two processes based on the determination. PH meter.   The pH meter according to any one of claims 1 to 3, wherein the previous calibration data erased during the calibration is automatically stored as a calibration history.   When overwriting the calibration data, the present calibration data is compared with the previous calibration data, and has a function of automatically determining whether or not it is within a preset appropriate range. Item 5. The pH meter according to any one of Items 1 to 4. When the current calibration data is within the appropriate range, the previous calibration data is overwritten with the current calibration data, and when the current calibration data is outside the appropriate range, a process for requesting whether to overwrite or recalibrate is performed. The pH meter according to claim 5, wherein

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