JPS6346840Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a PH meter calibration device for inspecting or calibrating the indicator, glass electrode deterioration, and converter in a glass electrode type PH meter.

A glass electrode type PH meter that detects the PH value by detecting the voltage of a glass electrode sensor placed in the liquid to be measured.
However, the reliability of the PH meter may decrease due to deterioration in the performance of the glass electrode or errors in the indicator.

Therefore, conventionally, in order to calibrate the indicator of a PH meter, a reference voltage setting device that generates a reference voltage was provided.
A calibration device has been developed that selects an accurate calibration voltage corresponding to each PH value generated from a glass electrode by switching a switch and applies it from an output terminal to an electrode connection terminal of a PH meter. Furthermore, as a checker for glass electrodes, a checker has been developed that displays the output voltage of a glass electrode immersed in a liquid with a predetermined PH value using a movable ring type indicator, but each calibration device and checker of this type has a separate Since it has only one function, it is inconvenient to handle, and because it does not have a self-calibration function, it has the disadvantage that it is not possible to confirm accuracy during calibration or checking.

Focusing on the above-mentioned shortcomings, this device can functionally calibrate the indicator of a PH meter and inspect the performance deterioration of glass electrodes, etc. with one device, and also allows self-calibration of the device itself. The purpose of this invention is to provide a calibration device for a PH meter.

To this end, the present invention includes a reference voltage generator that generates a reference voltage corresponding to the PH value and outputs it via a selection switch, and a voltage signal for each PH value that corresponds to the electromotive force of the glass electrode. Input the level converter to be converted, the output terminal that sends the voltage signal output from the level converter to the glass electrode terminal of the PH meter to be calibrated via a switchable high resistance, and the electromotive force of the glass electrode to be tested. An input terminal, an impedance converter that converts the impedance of the voltage signal input from the input terminal, and a voltage converter that converts the impedance-converted input voltage signal into a voltage that indicates the PH value.
The voltage signals from the PH converter, impedance converter, voltage-PH converter, and the reference voltage generator are
It is equipped with a digital voltmeter that selectively displays PH value or voltage value.

Hereinafter, embodiments of this invention will be described based on the drawings.

Figure 1 shows an external view of the PH meter calibration device, and Figure 2 shows a block diagram of its electric circuit. 1 is PH
A reference voltage generator generates a reference voltage corresponding to a value, and outputs the reference voltage via a selection switch 2 that selects PH1 to PH13. 3 is a level converter that inputs this reference voltage and converts it into a test voltage for each PH value corresponding to the electromotive force of the glass electrode.For example, when the PH is measured at 20℃ with a glass electrode, the theoretical value generated at the glass electrode. Generates a voltage as This voltage signal is sent to the output terminal 6 to be calibrated via a changeover switch 4 that switches a high resistance 5 from 0.1MΩ to 500MΩ.
An output circuit is formed to output to the PH meter.

7 is an input terminal used when inspecting the performance deterioration of the glass electrode. An impedance converter 8 is connected to the input terminal 7, and the output side of the impedance converter 8 converts the input voltage signal into a PH value. A voltage-PH converter 9 that converts into a corresponding voltage (voltage for displaying as a PH value) is connected. 10 is a digital voltmeter that displays the electromotive force of the inspected glass electrode as it is in units of mV, and also inputs the voltage signal for the PH value converted by the voltage-PH converter 9 to display it as a PH value. indicate. 11 is a display changeover switch that switches between this mV display and PH display, and "OUT" displays the reference voltage value corresponding to the PH value output from the reference voltage generator 1 as is.
It also has a switching contact. Reference numeral 13 denotes a power supply circuit equipped with a dry battery, which supplies constant voltage power to the reference voltage generator 1 , digital voltmeter 10 , voltage-PH converter 9 , and impedance converter 8 . 12 is a zero adjuster when displaying the PH value with a digital voltmeter,
Focusing on the fact that the electromotive force of the glass electrode is zero when PH7 is detected, when the input terminal 7 and the common terminal 14 are shorted and the changeover switch 11 is set to the PH position, the digital voltmeter 10 will display 7.00. Adjust as follows.

Next, the manner of use of the PH meter calibration device having the above configuration will be explained.

First, when calibrating the indicator or converter of a PH meter, connect the output terminal 6 and common terminal 14 of the calibration device to the glass electrode terminal and reference electrode terminal of the PH meter to be calibrated, and set the changeover switch 11 to "OUT". position,
Set the resistance selector switch 4 to the "100MΩ" position, and in this state, set the selection switch 2 to PH1 - PH.
While switching up to 13, record the PH value reading indicated on the indicator of the PH meter. At this time, the digital voltmeter 10 of the calibration device receives a reference voltage of 100 mV per 1 PH generated from the reference voltage generator 1, for example.
If selection switch 2 is selected for PH4,
Display 400mV as 4.00PH. Therefore, the function of the reference voltage generator 1 can be checked, and if this display is off, the reference voltage generator 1
This will be calibrated by adjusting the variable resistance inside. On the other hand, if the PH value indicated by the indicator of the PH meter deviates from the value selected by the selection switch 2, the PH meter is readjusted to correct this deviation. In addition,
When selecting switch 2 is set to PH1 or PH13 and switching switch 4 is sequentially switched from 100MΩ to 500MΩ, if there is a change of 0.5PH or more in the indicator of the PH meter, there may be an insulation failure in the input circuit of that indicator. It can be determined that there is an abnormality.

Next, when inspecting the performance deterioration of the glass electrode, connect the lead wire of the glass electrode to the input terminal 7, the lead wire of the comparison electrode to the common terminal 14, and set the changeover switch 11 to the "mV" position or PH When displaying, set it to the "PH" position. Therefore, when the glass electrode and the reference electrode are immersed in a known liquid, such as steaming water with a pH of 7, check whether the display on the digital voltmeter 10 is 7.00.If there is a deviation of more than a predetermined error, It is determined that the glass electrode has deteriorated.

For self-calibration or self-check of the input system including the impedance converter 5 and voltage-PH converter 6, short-circuit the output terminal 6 and input terminal 7 of the calibration device and set the changeover switch 11 to the "PH" position. This can be easily done. In this case, a reference voltage corresponding to, for example, PH4 is sent from the reference voltage generation circuit 1 to the level converter 3.
A voltage signal corresponding to the electromotive force of the glass electrode at PH4 is input to the impedance converter 8 via the output terminal 6 and input terminal 7, and the voltage signal impedance-converted here is input to the voltage-PH converter. 9 and is converted into a voltage signal for displaying the corresponding PH value, and then applied to a digital voltmeter 10. In this way, when the calibration device is functioning normally, the digital voltmeter 10 displays 4.00PH selected by the selection switch 2.
When the displayed PH value deviates, the circuits such as the level converter 3 and voltage-PH converter 6 are readjusted and calibrated.

As explained above, according to the PH meter calibration device of this invention, it is possible to easily calibrate the PH meter and check the glass electrode in various ways with one device. You can check for poor insulation in the PH meter input circuit and indicator. Furthermore, self-calibration of the reference voltage generation circuit is easily possible, and by shorting the output terminal and input terminal, the functions of each circuit in the calibration device can be checked without using other instruments. Self-calibration of the circuit can be easily performed.

[Brief explanation of drawings]

The figures show an embodiment of this invention; FIG. 1 is an external perspective view of a PH meter calibration device, and FIG. 2 is a block diagram of the electric circuit of the same device. DESCRIPTION OF SYMBOLS 1... Reference voltage generation circuit, 3... Level converter, 5... High resistance, 6... Output terminal, 7... Input terminal, 8... Impedance converter, 9... Voltage-PH converter, 10 ...Digital voltmeter.

Claims (1)

[Scope of utility model registration request] a reference voltage generator that generates a reference voltage corresponding to the PH value and outputs it via a selection switch; a level converter that converts the reference voltage into a voltage signal for each PH value corresponding to the electromotive force of the glass electrode; An output terminal that sends the voltage signal output from the level converter to the glass electrode terminal of the PH meter under test via a switchable high resistance, an input terminal that inputs the electromotive force of the glass electrode under test, and an impedance converter that converts the impedance of the input voltage signal;
A voltage-PH converter that converts an impedance-converted input voltage signal to a voltage indicating a PH value, an impedance converter, a voltage-PH converter, and a voltage signal from the reference voltage generator are selected as a voltage value or a PH value. A calibration device for a PH meter characterized by being equipped with a digital voltmeter that displays a PH meter.