JP2002320676A - Oxygen thickener for medical use and sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen thickener capable of alarming to the user by detecting early defects of sensors and ensuring supply of oxygen. SOLUTION: The oxygen thickener for a medical use has a built-in sensor, and supplys oxygen concentrated air to the user by separating oxygen in air. The thickener is provided with an input voltage or an input current measured by the sensor and an input change means for another voltage or current inputting within the application range of the sensor. The means compares the outputs measured with each different inputs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a medical oxygen concentrator for separating oxygen in air and supplying oxygen-enriched air to a user such as a patient with a respiratory disease. More specifically, the present invention relates to an oxygen concentrating device capable of grasping before an abnormality of various sensors mounted for guaranteeing performance (concentration, flow rate, etc.) of supplied oxygen gas becomes apparent.

[0002]

2. Description of the Related Art Conventionally, oxygen inhalation therapy for inhaling oxygen has been performed for patients with chronic respiratory diseases such as sequelae of pulmonary tuberculosis and pulmonary hypertension, and an oxygen concentrator for separating oxygen from the air has been developed. . As such an oxygen concentrator, a membrane separation type oxygen concentrator using an oxygen selective permeable membrane and an adsorption type oxygen concentrator using an adsorbent capable of selectively adsorbing nitrogen or oxygen are known. Further, there is an apparatus that electrochemically generates oxygen using a solid electrolyte membrane that selectively transmits oxygen ions. As an adsorption-type oxygen concentrator, there is a pressure fluctuation adsorption-type oxygen concentrator using a compressor. Usually, compressed air is introduced by a compressor into an adsorbent bed filled with an adsorbent capable of selectively adsorbing nitrogen. An apparatus for obtaining an oxygen-enriched gas by alternately performing an adsorption step of obtaining an oxygen-enriched gas by adsorbing nitrogen in a state and a desorption step of desorbing nitrogen by reducing the internal pressure of the adsorption bed to regenerate the adsorbent. is there.

[0003]

In these oxygen concentrators, the performance (concentration, flow rate, etc.) of the supplied oxygen gas is
Various sensors are installed to guarantee the performance. Recently, sensors and electronic circuits have become complicated and precise control has been performed. While these sensors have advanced performance, they also have the disadvantage of being vulnerable to disturbances (electric noise, static electricity, vibration, heat, etc.). The performance degradation due to these disturbances proceeds without becoming apparent, and sometimes suddenly becomes abnormal.

[0004] Regarding oxygen concentrator performance abnormalities such as oxygen concentration, flow rate, abnormal pressure, temperature, abnormal current, etc., it is monitored that the output of various sensors is within a set value, and if the output deviates from a specified value, it is regarded as abnormal. A system that performs an alarm operation is used. There is also a method in which a plurality of set values are provided and a notice is transmitted with a forecast meaning. This is a so-called yellow signal and red signal level display. These are to compare the current value of performance with a preset value, and do not grasp the progress of deterioration of the sensor or the like.

SUMMARY OF THE INVENTION It is an object of the present invention to grasp in advance the progress of the deterioration of the performance of a sensor element for detecting even if the current value of the device performance does not cause any problem. It is intended to provide an oxygen concentrator that can detect such a characteristic defect of the sensor of the oxygen concentrator before it becomes apparent and notify the user with an alarm to reliably supply oxygen to the user. is there.

[0006]

The inventor of the present invention has made intensive studies on such a problem, and as a result, the sensor is driven under conditions different from normal measurement conditions, such as the minimum voltage and the maximum voltage within the rated voltage range of various sensors. By comparing the two, it was found that it is possible to select a sensor in which the sensor characteristics are inferior but not actualized.

That is, according to the present invention, there is provided an oxygen concentrator which incorporates a sensor element, separates oxygen in the air and supplies oxygen-enriched air to a user, comprising: a measuring input voltage value or a measuring input current value of the sensor element; Medical oxygen concentrator comprising: input value changing means for giving another input voltage value or input current value within the use range of the sensor element; and means for comparing output values measured at each input value. An apparatus is provided.

The present invention is also a medical oxygen concentrator wherein the sensor element is a photosensor, a zirconia oxygen concentration sensor, or a semiconductor pressure sensor, and the result of the comparing means is within a predetermined range. It is an object of the present invention to provide a medical oxygen concentrator characterized by comprising a display means for displaying when it comes off.

According to the present invention, there is provided an input changing means for applying at least two types of input voltage values or input current values to a sensor element within a use range thereof, and a measuring means for measuring an output value measured at each input value. The present invention also provides a sensor measuring device comprising a comparison means for comparing measurement results.

[0010] The present invention also provides a sensor measuring device characterized by comprising display means for displaying when the result of the comparing means is out of a predetermined range.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, at least two types of input voltages or input currents within an operating range are applied to individual sensors, and output values obtained from at least two types of input values are compared.

That is, the sensor inspection mode is set to, for example, C
When an attempt is made to perform the switching by a switching signal from the PU, data (transistor collector voltage, pressure voltage, concentration voltage in the photosensor) immediately before entering the inspection mode is stored in the RAM in the CPU. When the storage is completed normally, for example, the lowest rated voltage is applied to various sensors.

The switching between the steady-state rated voltage and the minimum rated voltage, or the switching between the steady-state rated current and the minimum rated current, can be switched by an analog switch, a multiplexer, or the like in response to a switching signal from the CPU. That is, the measured value measured at the lowest rated voltage or the lowest rated current and C
A comparison is made with the measured value at the normal rated voltage or the normal rated current stored in the RAM in the PU. In the case of photo sensors and zirconia type density sensors, the transistor collector voltage and density voltage in the photo sensor when the voltage is changed are compared with the measured values stored in the RAM. Is judged to be normal, that is, it means that the performance degradation has not progressed.If the measured values of both are out of the specified value set in advance, it is considered that the performance of the sensor itself has decreased, and the sensor deterioration alarm Lights up.

In the case of a pressure sensor, the output voltage varies depending on the current value driven by the pressure sensor.
The ratio of at least two types of input current values to be measured is compared with the output voltage measured at the two types of input current values. If the ratio is other than the predetermined value set in advance, it indicates that the pressure sensor is deteriorated or has a tendency to deteriorate.

In the method of judging the deterioration state of the sensor performance by changing the voltage value, the deterioration state of the sensor can be judged not only at the lowest rated voltage but also at the highest rated voltage. Is overloaded, and the life may be shortened. Therefore, the lowest rated voltage is preferable.

Similarly, in the method of judging the deterioration state of the sensor performance by changing the current value, the deterioration state of the sensor can be judged not only with the lowest rated current but also with the highest rated current. The sensor is overloaded and may have a reduced life, so the lowest rated current is preferred.

During normal operation, a mechanism may be used in which the check software operates temporarily to perform switching using hardware such as an analog switch, or the check software may be automatically operated before or during operation of the apparatus. Works,
It is also possible to switch between voltage and current.

It is not necessary to provide these check systems for all sensors, and it is a matter of course that it is only necessary to provide these check systems for particularly important sensor units or sensor units that are easily deteriorated when guaranteeing performance.

Alternatively, instead of providing the device with an automatic check function, as a device carried by a service person, a changeover switch is provided on the device main body to change an input voltage or an input current, so that it is possible to easily determine a sensor performance degradation state. It may be configured to be used as a checker.

Hereinafter, specific embodiments of the medical oxygen concentrator according to the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a schematic flow chart schematically showing a preferred embodiment of the medical oxygen concentrator according to the present invention. A pressure fluctuation adsorption type oxygen concentrating means is provided as an oxygen concentrating means, and a compressor 1 is connected to an adsorption tower 3 filled with zeolite 13X as an adsorbent for selectively adsorbing nitrogen through an automatic opening / closing valve 2, for example. A surge tank 9 for temporarily storing oxygen-enriched air is connected via an automatic on-off valve 4. The surge tank 9 is provided with a conduit for an oxygen-enriched air flow path equipped with a pressure reducing valve and the like. The conduit is provided with an oxygen concentration sensor 12 as oxygen concentration detecting means, and an orifice type flow rate setting means as flow control means. A vessel 8 is provided, to which oxygen-enriched air supply means such as a nasal cannula is connected.

FIG. 2 shows a circuit configuration of the photosensor 14 mounted in the oxygen concentrator. Such a photo sensor is a sensor that is installed in the flow rate setting device 8 and controls the flow rate display. Specifically, there is a reflector above the four photosensors, and the output of the photosensor becomes a digital output H / L depending on the presence or absence of reflection.
The flow value is decoded by the combination of. The power supply voltage 13 of the photo sensor 14 is normally driven at +5 V. However, in the sensor inspection mode, the power supply voltage 13 is, for example, + 5V.
Reduce to 3V. After the collector voltage value of the phototransistor 16 in the photosensor 14 at the steady rated power supply voltage is held in the RAM in the CPU, the sensor inspection mode is switched by a CPU signal (not shown) to lower the power supply voltage 13. When the photosensor 14 has deteriorated, the irradiation amount of the light emitting diode 15 in the photosensor 14 decreases as the power supply voltage 13 decreases, and the collector voltage of the phototransistor 16 in the photosensor 14 starts to gradually increase. As a result, the ratio between the collector voltage value of the phototransistor 16 in the photosensor 14 when the power supply voltage is reduced and the collector voltage of the phototransistor 16 in the photosensor 14 at the time of the normal rated voltage +5 V stored in the RAM. And if it is within a predetermined value, it is determined that the performance of the photo sensor has not been reduced. However, if the value becomes other than the preset specified value, it indicates that the performance of the photosensor is starting to deteriorate, and it is necessary to replace the sensor before the phenomenon becomes apparent.

FIG. 3 shows a circuit configuration of a pressure sensor mounted in the oxygen concentrator. After the pressure voltage value at the steady-state rated current value is held in the RAM in the CPU, the sensor inspection mode is switched by the signal 19 from the CPU to reduce the current value. That is, since the pressure sensor is driven by a constant current, a current lower than the steady-state rated current value is supplied in the sensor inspection mode. For that, C
A voltage lower than the normal rated voltage is applied to the operational amplifier 25 based on the signal 19 from the PU to drive a constant current circuit lower than the normal rated current value. The pressure voltage value at that time is compared with the pressure voltage value in the steady state stored in the RAM, and if the ratio of the voltage ratio to the steady current value and the reduced current value is within the predetermined value set in advance, it is normal. It can be determined that there is.
However, if the ratio between the two is other than the predetermined value, it indicates that the pressure sensor is abnormal for some reason.

Similarly, FIG. 4 shows a circuit configuration of a zirconia-type concentration sensor mounted in the oxygen concentrator. In the density sensor, as shown in FIG. 5, the shoulder characteristics are rounded due to aging, and the current flat region starts to decrease. Alternatively, it is known that when impurities are accumulated near the sensor electrode, a current-voltage characteristic having no flat region as shown in FIG. 6 is exhibited. Therefore, by applying a bias voltage different from the bias voltage at the time of measurement to the concentration sensor, it is possible to determine the deterioration state.

For example, in the sensor inspection mode, the bias voltage value is applied lower than the steady-state bias voltage value. After the concentration voltage value at the steady bias voltage is stored in the RAM in the CPU, the sensor inspection mode switching
A signal 29 from U and the analog switch 28 are used to lower the bias voltage. The density voltage value at that time is compared with the density voltage stored in the RAM, and if the ratio between the two is within a preset specified value, it is determined to be normal. The sensor needs to be replaced before the phenomenon becomes evident, suggesting that the performance of the is beginning to decline.

[0026]

By using the medical oxygen concentrator of the present invention, such a check is automatically incorporated into the circuit, and is performed in a method different from the method for notifying the user that the sensor performance defect is progressing. Since it can be notified, preventive maintenance can be performed, and treatment can be performed before it becomes apparent, it can be performed without bothering the user.

[Brief description of the drawings]

FIG. 1 is a flowchart of a medical oxygen concentrator.

FIG. 2 is a circuit configuration of a photosensor.

FIG. 3 is a circuit configuration of a pressure sensor.

FIG. 4 is a circuit configuration of an oxygen sensor.

FIG. 5 is a conceptual diagram of an oxygen sensor voltage vs. current characteristic when deterioration occurs.

FIG. 6 is a conceptual diagram of an oxygen sensor voltage vs. current characteristic when impurities are accumulated near an electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2, 4, 5 Automatic opening / closing valve 3 Adsorption tower 6 Pressure regulating valve 7 Bactericidal filter 8 Flow rate setting device (including photo sensor) 9 Surge tank 10 Oxygen-enriched air 11 Pressure sensor 12 Oxygen concentration sensor 13 Photo sensor power supply voltage 14 Photo Sensor 15 Light-emitting diode 16 Phototransistor 17 Comparator 18 Resistance 19 Signal from CPU 20 Constant voltage diode 21, 26 Transistor 22 Resistance 23 Pressure sensor power supply voltage 24, 25 Operational amplifier 27 Oxygen sensor power supply voltage 28 Analog switch 29 Signal from CPU 30 Oxygen sensor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C086 AA34 AA38 BA07 CA02 CA03 CA15 CB15 CB20 CB40 DA03 DA08 DA22 EA11 EA41 EA45 FA11

Claims (5)

[Claims] An oxygen concentrator incorporating a sensor element for separating oxygen in the air and supplying oxygen-enriched air to a user, comprising: a measuring input voltage value or a measuring input current value of the sensor element; An input value changing means for giving another input voltage value or input current value within a use range,
A medical oxygen concentrator characterized by comprising means for comparing output values measured with respective input values. 2. The medical oxygen concentrator according to claim 1, wherein the sensor element is a photo sensor, a zirconia oxygen concentration sensor, or a semiconductor pressure sensor. 3. The medical oxygen concentrator according to claim 1, further comprising display means for displaying when the result of said comparison means is out of a predetermined range. 4. An input changing means for applying at least two types of input voltage values or input current values within a use range to a sensor element, a measuring means for measuring an output value measured at each input value, and a measurement result. Sensor measuring device comprising comparison means for comparing 5. The sensor measuring device according to claim 4, further comprising display means for displaying when the result of said comparing means is out of a predetermined range.