JPS63143036A - Calibration apparatus of sensor for measuring gas partial pressure - 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] [Field of Industrial Application] The present invention relates to a calibration device for a sensor for measuring gas partial pressure, and in particular, a calibration device for a sensor for measuring a transcutaneous carbon dioxide gas partial pressure in an atmosphere of two or more types of standard gases. The present invention relates to a calibration device for a gas partial pressure measurement sensor that calibrates output.

[Prior art] Transcutaneous oxygen partial pressure measuring sensor, transcutaneous carbon dioxide partial pressure measuring sensor, transcutaneous oxygen partial pressure measuring sensor/transcutaneous carbon dioxide gas partial pressure measuring gas partial pressure such as carbon dioxide gas and oxygen gas in blood Measurement is widely performed using electrochemical sensors such as sensors for measuring partial pressure. When gas partial pressure is measured using such an electrochemical sensor, the measurement is performed while calibrating the sensor in order to maintain measurement accuracy. The following will explain the measurement of carbon dioxide gas partial pressure (hereinafter referred to as PCO2) as an example. Since the PCO□ sensor shows a constant value for gases with the same PCO2 value, it is recommended to use a known PCO2 standard gas, that is, generally an air mixture gas with two types of carbon dioxide concentrations (hereinafter referred to as low gas and high gas). Automatic calibration is performed using a two-point calibration method.

[Problems to be Solved by the Invention] By the way, in the case of the conventional automatic calibration device for the PCO2 sensor, if the PCO2 sensor is left in the air for a long time and then calibrated, the PCO□ sensor becomes unstable in the standard gas atmosphere. There was a problem in that it took a long time for the process to change.

Furthermore, even during measurements after calibration, the stability of the PCO2 sensor was poor, which sometimes caused problems in measurement accuracy. In order to solve these problems, a method of storing the PCO2 sensor in a low gas atmosphere or a high gas atmosphere has been adopted, but this also has the problem of increasing gas consumption. .

Therefore, the main object of the present invention is to improve measurement accuracy after storage and reduce gas consumption by intermittently placing a gas partial pressure measurement sensor in a standard gas atmosphere during storage. An object of the present invention is to provide a calibration device for a sensor for measuring gas partial pressure.

[Means for Solving the Problems] The present invention is a gas partial pressure measurement sensor calibration device that calibrates a gas partial pressure measurement sensor in an atmosphere of two or more types of standard gases. There are two types of gas circuits: a standard gas supply source that supplies gas, and a gas circuit that leads the standard gas from the standard gas supply source to the sensor mounting part on which the gas partial pressure measurement sensor to be calibrated is mounted. A gas switching means for selecting the above standard gas and supplying it to the gas circuit, a time measuring means for measuring the supply time of the selected standard gas, and a gas partial pressure measuring sensor are mounted on the sensor mounting part. and a standard to be supplied every time a predetermined time is measured in response to input by the input means that the gas partial pressure measurement sensor is placed on the sensor mounting section. and control means for determining the gas and controlling the gas switching means to supply the determined standard gas.

[Function] The gas partial pressure measurement sensor calibration device according to the present invention has the following features:
Calibration or measurement after storage can be performed by placing a gas partial pressure measurement sensor in an atmosphere of one of more than one type of standard gas, and intermittently switching and supplying the standard gas every time a predetermined time is measured. The heirloom value of the gas partial pressure measurement sensor can be improved.

[Embodiment of the Invention FIG. 1 is a diagram for explaining the invention in detail. In this invention, as shown in FIG. 1, the gas supply time measuring means 1 measures the time during which high gas or low gas is supplied, and the sensor set input means 2 allows the PCO (referred to as sensor spot). Then, the gas supply state control means 3 drives the gas switching means, so that when the PCO□ sensor is set at the sensor spot and calibration has not been performed, the PCO2 sensor is intermittently placed in a low gas atmosphere or a high gas atmosphere. allows you to place it in

FIG. 2 is a schematic block diagram of an embodiment of the present invention,
FIG. 3 is a piping diagram of a gas circuit in one embodiment of the present invention, and FIG. 4 is a diagram showing the configuration of a sensor spot.

First, the configuration of an embodiment of the present invention will be described with reference to FIGS. 2 to 4. The PCO□ sensor 5 is placed on the sensor spot 27 in a standard gas atmosphere, and its output is given to the A/D converter 6 and converted into a digital signal. This digital signal is given to the CPU 12 via the input port 7. The input boat 7 includes a low gas supply abnormality detection pressure switch 8, a high gas supply abnormality detection pressure switch 9, a sensor set switch 10, and an automatic calibration execution procedure changeover switch 11.
are connected. One contact of these switches 8 to 11 is connected to the power supply Vcc, and the other contact is grounded.

The low gas supply abnormality detection pressure switch 8 and the high gas supply abnormality detection pressure switch 9 are connected to the gas circuit shown in FIG.

This shows a state in which high gas is being supplied normally. Then, when an abnormality in the supply of raw gas occurs and the pressure in the piping of the gas circuit becomes below a certain value, the pressure switch 8 for detecting abnormality in raw gas supply is switched to the contact on the power supply Vce side. Similarly, the pressure switch 9 for detecting high gas supply abnormality can also be used when an abnormality occurs in the high gas supply.
The contact is switched to the power supply Vce side. The sensor set switch 10 is used to input that the PCO2 sensor 5 is set at a sensor spot 27, which will be explained later in FIG. 3. The automatic calibration execution procedure changeover switch 11 is used to select execution of low calibration or high calibration.

The aforementioned input port 7 is connected to the CPU 12, as well as a clock generator 13, a ROM 14, and a RAM.
15 and an output boat 16 are connected. ROM
14 stores in advance a program for controlling the CPU 12, and according to this program, the CPU 12 takes in necessary data from the input port 7, exchanges data with the RAM 15,
Alternatively, time is counted as an interrupt process using a clock signal given from the clock generator 13, and necessary data is output to the output port 16. The output boat 16 includes a display section 17 and three-way solenoid valves 18 and 19.
is connected. The display unit 17 displays a message indicating an abnormality in the supply of low gas or abnormality in the supply of high gas in accordance with the signal given from the output boat 16. The three-way solenoid valves 18 and 19 switch between supplying high gas or low gas based on the output of the output boat 16.

Next, the configuration of the gas circuit will be explained with reference to FIG. The low gas cylinder 21 supplies low gas, and the high gas cylinder 22 supplies high gas. The low gas cylinder 21 and the high gas cylinder 22 are each connected to pressure regulators 23 and 24 via piping. These pressure regulators 23 and 24 each supply approximately 1.5 kg/low gas and high gas.
The pressure is adjusted to Cm2. Furthermore, a low gas supply abnormality detection pressure switch 8 and a high gas supply abnormality detection pressure switch 9 are connected to the outlet sides of the pressure regulators 23 and 24 via piping.

Furthermore, flow regulators 25 and 26 are connected to the low gas supply abnormality detection pressure switch 8 and the high gas supply abnormality detection pressure switch 9 via piping. These styles I
The JJ regulators 25 and 26 are used to adjust the flow rate of low gas and high gas to approximately 5 m (j/min).On the outlet side of these flow regulators 25 and 26, there is a three-way electromagnetic connector not shown in Fig. 1 above. Valves 18 and 19 are connected, and a sensor spot 27 is connected to the outlet sides of the three-way solenoid valves 18 and 19.

This sensor spot 27 is for calibrating the PCO2 sensor 5 by placing the PCO□ sensor 5 thereon.

This sensor spot 27 is configured as shown in FIG. That is, the low gas or high gas led from the gas circuit explained in FIG.
3 to the gas reservoir 272, and the sensitive surface 51 of the PCO□ sensor 5 is placed in a low gas atmosphere or a high gas atmosphere. The gas outlet passage 274 has the purpose of keeping the pressure inside the gas reservoir 272 almost equal to atmospheric pressure, and
It is provided for the purpose of expediting gas exchange within the tank.

Also, due to the tension of the spring 276, the rotating arm 27
5 connects the PCO□ sensor 5 to the ring-shaped packing 271.
By applying pressure to the sensor spot 27, gas is prevented from leaking between the PCO2 sensor 5 and the sensor spot 27.

FIG. 5 is a flow diagram showing an automatic calibration stop routine for explaining the specific operation of an embodiment of the present invention, and FIG. 6 is a flow diagram showing the automatic calibration routine as well.
FIG. 7 is a flowchart showing the standby routine, and FIG. 8 is a flowchart showing the clock signal interrupt processing routine.

Next, with reference to FIGS. 2 to 8, specific operations of an embodiment of the present invention will be described.

First, when the power is turned on, the automatic calibration stop program shown in FIG. 5 starts. That is, the CPU 12 performs step (abbreviated as SP in the figure) SPI,
Three-way solenoid valve 18.19 via output port 16
to close these three-way solenoid valves 18,19. Next, in step SP2, the CPU 12 reads the state of the sensor switch 1G via the input port 7 and determines whether a set of sensors has been selected.

This determination is made by the user placing the PCO2 sensor 5 on the sensor spot 27 and operating the sensor set switch 10.
The automatic calibration is repeated until it is selected to be performed.

When the sensor set is selected, the CPU 12 proceeds to step S.
At P3, it is determined whether or not the low gas supply is normal, and at step SP5, it is determined whether or not the high gas supply is normal.

These determinations are made by reading the states of the low gas supply abnormality detection pressure switch 8 and the high gas supply abnormality detection pressure switch 9 through the input port 4. That is, if the output voltages of the low gas supply abnormality detection pressure switch 8 and the high gas supply abnormality detection pressure switch 9 are the same as the potential of the power supply Vcc, it is determined that the supply is abnormal, and if the output voltage is Ov, the supply is normal. It is determined that

If the CPU 2 determines that the supply of raw gas is abnormal, it displays a message indicating that the supply of raw gas is abnormal on the display unit 17 in step SP4.

Further, if the supply of high gas is abnormal, the CPU 12 displays a message indicating that the supply of high gas is abnormal on the display section 17 in step SP6. However, if it is determined in steps SP3 and SP5 that both the low gas and high gas supplies are normal, the automatic calibration program shown in FIG. 6 is executed in step SP7.

In the automatic calibration program shown in FIG.
In step 5PII, time counter 1, which is a variable for counting time, is cleared. This variable is R
AM15 and C from the clock generator 13.
It is incremented by an interrupt process (FIG. 8) executed by a clock signal manually input to the PU 12 at a constant cycle. Furthermore, in step 5P12, the CPU 12 opens the three-way solenoid valve 18 and closes the three-way solenoid valve 19 to supply raw gas to the sensor spot 27.

After that, in step 5P13, the CPU 12 determines whether or not the raw gas supply is normal. If the raw gas supply is normal, the value of time counter 1 is determined in step 5P15, and it is determined whether 10 hours have elapsed. If 17 hours have not passed, step S1
Return to step 2, and repeat step 5P12 until T, time elapses.
Repeat the operations of 5PI3 and 5P15. This is an operation for waiting until the sensor spot 27 is in a low gas atmosphere and the PCO2 sensor 5 placed on the sensor spot 27 is stabilized in the low gas atmosphere. T. If the supply of raw gas becomes abnormal before the elapse of time, the CPU 12 proceeds to step 5P14 and performs the fifth step described above.
Execute the automatic calibration stop program explained in the figure.

When the CPU 12 determines in step 5P15 that 18 hours have elapsed, the CPU 12 outputs the PCO2 sensor 5 via the input port 7 in step 5P16.
The output voltage is converted into a digital signal by the A/D converter 6, and the value PL is read and stored in the RAM 15. In addition, P
When measuring PCO□ with the CO2 sensor 5, P
The output voltage of the CO2 sensor 5, the value PL stored in the RAM 15, and the RA in step 5P24 described later
PCO2 is calculated by the value P stored in M15. In step SF'17, the CPU 12 determines whether the automatic calibration execution procedure changeover switch 11 is turned on. That is, when the output voltage of the automatic calibration execution procedure changeover switch 11 input via the input boat 4 is Ov, the standby operation shown in FIG. 7 is performed, and the output voltage of the automatic calibration execution procedure changeover switch 11 becomes Vcc. In this case, perform the following operations.

That is, the CPU 12 clears the time counter 1 in step S P 1'9, closes the three-way solenoid valve 18 in step S5P20, and opens the three-way solenoid valve 19 to supply high gas to the sensor spot 27. Thereafter, in step 5P21, the CPU 12 determines whether high gas is being supplied normally.

If the high gas supply is normal, the value of the time counter is determined in step SP23, and it is determined whether 12 hours have elapsed. If 12 hours have not elapsed, the operations of steps SP21 and 5P23 are repeated. If the high gas supply becomes abnormal before 12 hours have elapsed, the process proceeds to step 5P22 and an automatic calibration stop operation is executed. In step 5P23, if 12 hours have elapsed, the process advances to step 5P24, where the PCO2 input via the input boat 4
The value P obtained by converting the output voltage of the sensor 5 by the A/D converter 6
, and store it in the RAM 15, Step 5P25
performs standby operations.

Next, the standby operation will be explained with reference to FIG.

In the standby operation, the CPU 12 clears time counter 1 in step 5P31, and clears time counter 2 in step 5P32. This time counter 2 is a variable that has the same function as time counter 1, and has a RAM
15 is stored programmatically. Next, CPU1
2 opens the three-way solenoid valve 18 in step 5P33 to start supplying raw gas, and in step 5P34 it is determined whether or not the raw gas supply is normal. Then, in step SP36, the value of the time counter 2 is determined to determine whether or not T1 time has elapsed since the start of raw gas supply. If 18 hours have not elapsed, the operations of steps 5P34 and 5P36 are repeated. If the raw gas supply becomes abnormal before the T1 time elapses, the automatic calibration stop program shown in FIG. 5 is executed. However, in step 5P36, the CPU 12
When it is determined that 5 hours have passed, step 5P37
In step 5P3, clear time counter 2.
At step 8, the three-way solenoid valve 18 is closed to stop the supply of raw gas.

Further, in step 5P39, the CPU 12 determines whether or not the time counter 2 has counted 19 hours.
Wait until the time has elapsed. CPU12 is step 5
When it is determined in P39 that the time counter 2 has counted 19 hours, it is determined in step SP40 whether or not the time counter 1 has counted T hours. T,
If the time has not elapsed, proceed to step 5P32 described above.
The process returns to step 5P32 to step 5P40 until 18 hours have elapsed. Then, when the time counter 1 counts the time T, step SP41
Run the automatic calibration program.

Next, the clock signal interrupt processing routine will be explained with reference to FIG. This clock signal interrupt processing routine is such that when a clock signal is input from the clock generator 13 to the PU 12, the program being executed at that time is temporarily interrupted and the clock signal interrupt processing routine is executed. Once completed, execution of the interrupted program will resume. The CPU 12 performs steps 5P51 and 5
At P52, the value of the variable time counter 12 hour counter 2 stored in the RAM 15 is incremented by one. Next, in step SP53, the sensor switch 5
If the sensor is set, the interrupt processing is terminated and execution of the interrupted program is resumed. However, if the sensor switch is off, the process proceeds to step 5P54 without resuming execution of the interrupted program;
Execute the automatic calibration stop program shown in FIG.

FIGS. 98 to 9C are diagrams showing potential changes of the PCO2 sensor in an embodiment of the present invention.

In FIG. 9A, point a indicates the point in time when the automatic calibration operation is completed, and a standby operation is performed thereafter. Point b indicates the time point when waiting raw gas supply is started, point 0 indicates the time point when raw gas supply is stopped, and point d indicates the time point when automatic calibration operation is started. After the second automatic calibration is completed, the PCO2 sensor 5 is placed in a low gas atmosphere as a measurement simulation experiment.

Figure 9B shows that while waiting after the first automatic calibration,
It shows the potential change of the PCO2 sensor 5 when no raw gas is supplied, and similarly to FIG. 9A, the PCO□ sensor 5 is placed in a raw gas atmosphere after the second automatic calibration is completed.

FIG. 9C shows the potential change of the PCO2 sensor 5 when raw gas is continued to be supplied during standby after the first automatic calibration is completed. This figure 9C also shows figures 9A and 9B.
In the same way as shown in the figure, after the second automatic calibration, the PCO
□Sensor 5 is placed in a low gas atmosphere.

Comparing the example shown in FIG. 9A and the example shown in FIG. 9B, the example shown in FIG. 9A is more effective at stabilizing pco and sensor 5 during calibration than the example shown in FIG. The time required is shorter. Furthermore, in the results of a simulation test of measurements conducted after the completion of calibration, in the case of FIG. 9B, the initial drift 3 hours after the start of the simulation test measurement was 25%.

In FIG. 9A, almost no drift was observed, similar to the example in FIG. 9C. Furthermore, in the example shown in FIG. 9A, the ratio of the raw gas supply time to the gas supply stop time is set to 1.
=30 to 1:40, and the amount of gas consumed during standby is 1/30 to 1/40 of the example shown in FIG. 9C.

In addition, in the above-mentioned embodiment, the case where this invention is applied to a PCO2 sensor was explained, but it is not limited to this, and it can be applied to a transcutaneous oxygen partial pressure measurement sensor, a transcutaneous oxygen partial pressure measurement sensor, and a transcutaneous carbon dioxide gas partial pressure measurement sensor. Of course, the invention may also be applied to a combination of sensors.

[Effects of the Invention] As described above, according to the present invention, the gas partial pressure measurement sensor placed on the sensor placement part during storage is intermittently brought into a standard gas atmosphere at predetermined intervals. , the measurement accuracy after storage can be improved, and the amount of gas consumed can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the invention in detail. FIG. 2 is a schematic block diagram of an embodiment of the present invention. FIG. 3 is a diagram showing piping of a gas circuit in one embodiment of the present invention. FIG. 4 is a diagram showing the configuration of the sensor spot. 5 to 8 are flowcharts for explaining the specific operation of one embodiment of the present invention, and in particular, FIG.
6 shows the automatic calibration stop routine, FIG. 6 shows the automatic calibration routine, FIG. 7 shows the standby routine, and FIG. 8 shows the clock signal interrupt processing routine. FIGS. 98 to 9C are diagrams showing potential changes of the PCO2 sensor in an embodiment of the present invention. In the figure, 5 is a PCO2 sensor, 6 is an A/D converter,
7 is an input port, 8 is a pressure switch for detecting low gas supply abnormality, 9 is a pressure switch for detecting high gas supply abnormality, 10 is a sensor set switch, 11 is an automatic calibration execution procedure changeover switch, 12 is a CPU 113 is a clock generator, 14 is a ROM115 is RAM, 16 is an output port, 17 is a display, 18.19 is a three-way solenoid valve, 21 is a low gas cylinder, 22 is a high gas cylinder, 23°24 is a pressure regulator, 25.26 is a flow rate regulator, 27 is Shows sensor spot. Figure 3 21: 0 pieces are closed τ zz: 0 pieces are turned on. z759th page, page 27t゛SIF I shift'' Fig. 5 Fig. 8 Fig. 6 Fig. 7

Claims (2)

[Claims] (1) A calibration device for a gas partial pressure measurement sensor that calibrates a gas partial pressure measurement sensor in an atmosphere of two or more types of standard gases, the standard gas supply source supplying the two or more types of standard gases; a sensor mounting part on which a gas partial pressure measurement sensor to be calibrated is mounted and the gas partial pressure measurement sensor is placed in the standard gas atmosphere; from the standard gas supply source to the sensor mounting part; a gas circuit for guiding a standard gas; a gas switching means provided on the gas circuit for selecting the two or more types of standard gas and supplying it to the gas circuit; a supply time of the standard gas selected by the gas switching means; an input means for inputting that the gas partial pressure measurement sensor is placed on the sensor placement section; In response to input that the gas is placed on the unit, a standard gas to be supplied is determined every time a predetermined time is measured by the time measuring means, and the gas is supplied so as to supply the determined standard gas. A calibration device for a sensor for gas partial pressure measurement, comprising a control means for controlling a switching means. (2) The gas partial pressure measurement sensor includes a transcutaneous oxygen partial pressure measurement sensor, a transcutaneous carbon dioxide partial pressure measurement sensor, and a transcutaneous oxygen partial pressure measurement sensor/transcutaneous carbon dioxide partial pressure measurement sensor. A calibration device for a sensor for gas partial pressure measurement according to claim 1, which is any one of the above.