JP5416055B2 - TVOC detection method, detection apparatus, and outside air introduction amount control system - Google Patents

Description

  The present invention relates to a TVOC (Total Volatile Organic Compound) detection method, a detection apparatus, and an outside air introduction amount control system using a semiconductor sensor.

  Conventionally, it is known that temperature and humidity errors occur when measuring odor with a semiconductor sensor or the like. As a method of correcting this temperature / humidity error, for example, there are methods disclosed in Patent Documents 1 to 3.

  In the air purifier using the odor sensor of Patent Document 1, the output signal of the semiconductor sensor that is affected by the ambient temperature and humidity is corrected by the output signal of the infrared sensor that can select and detect a plurality of specific wavelengths. .

  Further, in the odor gas measuring apparatus of Patent Document 2, air having an absolute humidity equal to the absolute humidity of the measuring gas is manufactured and used as standard air for setting a zero value, thereby correcting the influence of moisture from the measured value. doing.

  The temperature / humidity corrector for odor / gas analysis of Patent Document 3 corrects the temperature / humidity error by making the temperature / humidity of the measurement gas and the standard air equal.

  On the other hand, the present inventor has already provided an outside air introduction amount control system shown in Patent Document 4. This system performs control to increase the amount of outside air introduced when the TVOC concentration value measured by the simple TVOC sensor becomes a predetermined value or more. As the simple TVOC sensor, there are various types including a semiconductor sensor. These sensors can be used.

JP 2001-74682 A JP-A-5-107167 Japanese Utility Model Publication No. 6-28702 JP 2008-190760 A

  By the way, in the detection of indoor TVOC, it is generally difficult to detect the required concentration of TVOC because various sensors including a semiconductor sensor are insufficient in sensitivity. Further, even if an attempt is made to obtain an output due to a lack of sensitivity of the sensor by increasing the amplification factor of the sensor amplifier (amplifier), the influence of disturbance such as temperature and humidity exceeded the output of the sensor by the detection target and was not practical. For this reason, development of the technique which can detect TVOC accurately was desired.

  The present invention has been made in view of the above, and an object of the present invention is to provide a TVOC detection method, a detection apparatus, and an outside air introduction amount control system capable of accurately detecting TVOC.

  In order to solve the above-described problems and achieve the object, a TVOC detection method according to claim 1 of the present invention is a method for detecting a TVOC concentration in a room using a semiconductor sensor, A sensitivity curve indicating the relationship between the concentration and the output signal of the semiconductor sensor is obtained in advance for each absolute humidity, and when the indoor TVOC concentration is detected by the semiconductor sensor, the temperature and humidity sensor simultaneously uses the semiconductor type sensor. The temperature / humidity of the sensor position is measured, the absolute humidity is obtained based on the measured value, the TVOC concentration corresponding to the output signal of the semiconductor sensor is read from the sensitivity curve corresponding to the absolute humidity, and the read TVOC concentration The output signal corresponding to is read from a sensitivity curve defined as a true value, and this output signal is used as a correction value to correct temperature and humidity errors in the output signal of the semiconductor sensor. And butterflies.

  According to claim 2 of the present invention, the TVOC detection method according to claim 1 corrects the drift of the sensor amplifier of the measurement system accompanying the output fluctuation due to temperature based on the measurement value of the temperature and humidity sensor. It is characterized by.

According to a third aspect of the present invention, there is provided a TVOC detecting device for detecting a TVOC concentration in a room using a semiconductor sensor, wherein the TVOC concentration in the room is detected by the semiconductor sensor. A temperature / humidity sensor for measuring the temperature / humidity at the position of the semiconductor sensor, and a microcomputer electrically connected to the semiconductor sensor and the temperature / humidity sensor. A sensitivity curve indicating the relationship between the TVOC concentration prepared in advance for each humidity and the output signal of the semiconductor sensor is stored, and the microcomputer obtains the absolute humidity based on the measured value of the temperature and humidity sensor. The TVO concentration corresponding to the output signal of the semiconductor sensor is read from the sensitivity curve corresponding to the absolute humidity, and the read TVO is read. An output signal corresponding to the concentration, read from the sensitivity curve was defined as the true value, and correcting the temperature and humidity error of the output signal of said semiconductor sensor the output signal as a correction value.

  According to claim 4 of the present invention, the TVOC detection device according to claim 3 corrects drift of the sensor amplifier of the measurement system accompanying output fluctuation due to temperature based on the measurement value of the temperature / humidity sensor. It is characterized by.

  An outside air introduction amount control system according to claim 5 of the present invention includes the TVOC detection device according to claim 3 or 4 described above, and controls the outside air introduction amount based on the detected value of TVOC. And

  An outside air introduction amount control system according to claim 6 of the present invention is characterized in that in claim 5 described above, the system further includes a plurality of odor sensors that measure a plurality of types of odors.

  The outside air introduction amount control system according to claim 7 of the present invention is characterized in that, in the above-described claim 6, the outside air introduction amount is controlled based on the detected odor value.

  According to the present invention, there is provided a method for detecting a TVOC concentration in a room using a semiconductor sensor, and a sensitivity curve indicating a relationship between the TVOC concentration and an output signal of the semiconductor sensor is previously determined for each absolute humidity. When the concentration of TVOC in the room is detected by the semiconductor sensor, the temperature and humidity at the position of the semiconductor sensor are simultaneously measured by the temperature and humidity sensor, and the absolute humidity is obtained based on the measured value. Read the TVOC concentration corresponding to the output signal of the semiconductor sensor from the sensitivity curve corresponding to humidity, read the output signal corresponding to the read TVOC concentration from the sensitivity curve defined as true value, and correct this output signal Since the temperature / humidity error of the output signal of the semiconductor sensor is corrected as a value, there is an effect that TVOC can be detected with high accuracy.

FIG. 1 is a diagram showing an embodiment of a TVOC detection method and detection apparatus according to the present invention. FIG. 2 is a diagram illustrating an example of a sensitivity curve and temperature / humidity correction. FIG. 3 is a diagram illustrating an example of a measurement result in a standard state. FIG. 4 is a diagram illustrating an example of a measurement result in a low humidity state. FIG. 5 is a diagram illustrating an example of outside air introduction amount control by an odor sensor.

  Hereinafter, embodiments of a TVOC detection method, a detection apparatus, and an outside air introduction amount control system according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

First, the idea that led to the present invention will be described.
The present inventor examined the results of long-term indoor air monitoring using a semiconductor sensor and the precise measurement results of TVOC, and the output from the semiconductor sensor was significant at the concentration required for each component contained in the TVOC. It was not a thing. However, in the vicinity of the concentration required for managing TVOC, it was found that there is a correlation between the semiconductor sensor output excluding the disturbance and the TVOC concentration.

  Semiconductor sensors are generally affected by temperature and humidity as disturbances, and output fluctuations that do not depend on TVOC exceed TVOC concentration changes. For this reason, only the output fluctuation by TVOC can be detected by correcting the temperature and humidity of the semiconductor sensor output and eliminating the disturbance. The present invention has been made based on such an idea.

  As shown in FIG. 1, a TVOC detection device 10 according to the present invention includes a semiconductor sensor 12 that detects the concentration of TVOC in a room 2, a temperature and humidity sensor 14 that measures the temperature and humidity at the position of the semiconductor sensor 12, A microcomputer 16 electrically connected thereto is provided.

  Here, the semiconductor sensor 12 and the temperature / humidity sensor 14 are arranged close to each other in the same unit 18. In this way, even if heat or the like is generated from the components in the unit 18 and the temperature and humidity in the unit 18 is different from the temperature and humidity in the room 2, the temperature and humidity error of the output signal of the semiconductor sensor 12 is highly accurate. It can be corrected with.

  The microcomputer 16 has an A / D and D / A conversion function, and outputs an output signal that has been subjected to temperature / humidity correction to the analog output and digital output via the signal lines 20 and 22.

  As described above, the output value (output signal) of the semiconductor sensor 12 varies depending on the temperature and humidity. Therefore, a sensitivity curve indicating the relationship between the TVOC concentration and the output signal of the semiconductor sensor is prepared in advance for each absolute humidity and stored in the memory of the microcomputer 16. In this case, for example, a value at which the output value of the semiconductor sensor 12 is minimized in standard (clean) air under a predetermined temperature and humidity condition (for example, relative humidity of 20 ° C. and 60% RH), and a detection target A sensitivity curve is created from the output value obtained with a constant concentration gas.

  In the present invention, when the concentration of TVOC in the room is detected by the semiconductor sensor, the temperature and humidity at the position of the semiconductor sensor are simultaneously measured by the temperature and humidity sensor, and the absolute humidity is obtained based on the measured value.

  Next, the TVOC concentration corresponding to the output signal of the semiconductor sensor is read from the sensitivity curve corresponding to the absolute humidity.

  Subsequently, an output signal corresponding to the read TVOC density is read from a sensitivity curve defined as a true value. Using this output signal as a correction value, the temperature and humidity error of the output signal of the semiconductor sensor is corrected. In this way, TVOC can be detected with high accuracy using a semiconductor sensor, and precise measurement of TVOC is not required.

  As described above, the temperature / humidity correction of the semiconductor sensor of the present invention defines the semiconductor sensor output value of the temperature / humidity condition as a true value, and the fluctuation of the output value due to the temperature / humidity of the semiconductor sensor The true semiconductor sensor value can be measured by converting the output value.

  Normally, when temperature and humidity correction is performed, if both temperature and humidity are factors that cause fluctuations in the output value, the output characteristics with the humidity changed for each temperature are measured, and the change is expressed by an approximate expression or the like. If this is the case, it is necessary to make corrections by creating a correction table (a correspondence table between sensor output values at temperature and humidity using semiconductor sensors and true values).

  The fluctuation of the output value due to the temperature and humidity of the semiconductor sensor mainly depends on the absolute humidity, and the fluctuation due to the temperature is small, so the absolute humidity is calculated from the temperature and humidity where the semiconductor sensor is placed, By converting the value to the value under the defined absolute humidity condition, it is not necessary to have a correction table in all temperature and humidity regions using the semiconductor sensor.

  For example, when the relative humidity is 20 ° C. and 60% RH, the absolute humidity is 10.366 g / kg ′. This is almost the same as the absolute humidity of 10.365 g / kg ′ when the relative humidity is 60 ° C. and 8% RH, and it is understood that no correction is necessary in this environment.

  Next, a specific method of creating a sensitivity curve and temperature / humidity correction will be described with reference to FIG.

(1) The output value at each concentration of the detection target gas (TVOC) of the semiconductor sensor (for example, detection target gas concentration 0 ppm, 1 ppm, 2 ppm, 5 ppm, 10 ppm, 20 ppm, 50 ppm, 100 ppm, 200 ppm, 500 ppm, 1000 ppm) , And measured by changing the absolute humidity (for example, 4.2 g / kg ′, 6.3 g / kg ′, 9.3 g / kg ′, 17.9 g / kg ′, 27.2 g / kg ′, 40.9 g). / Kg '), a sensitivity curve as shown in FIG. 2 is created. In FIG. 2, the horizontal axis represents the gas concentration, and the vertical axis represents the semiconductor sensor output value (voltage). Note that the change in absolute humidity needs to be measured for each different gas concentration because the semiconductor sensor output value does not change linearly with respect to the gas concentration.

(2) When the gas concentration is measured by the semiconductor sensor, the temperature and humidity are measured simultaneously by the temperature and humidity sensor, and the absolute humidity is calculated based on the measured value.

(3) The sensitivity curve at the absolute humidity of the calculation result is searched from the prepared sensitivity curve (FIG. 2). If there is no matching sensitivity curve, it is obtained by interpolation using a prepared sensitivity curve.

(4) The method of obtaining the sensitivity curve by interpolation obtains the value of the value at the absolute humidity at the time of measurement at each concentration by proportional conversion, and obtains it by linear interpolation connecting the points with a straight line.

(5) The gas concentration corresponding to the semiconductor sensor output value is obtained from the sensitivity curve created by interpolation, the voltage corresponding to this gas concentration is read from the true sensitivity curve, and this is used as the true value. Perform temperature / humidity correction of the output value.

(Specific method of temperature and humidity correction)
Next, a specific method of temperature and humidity correction will be described by taking as an example the case of obtaining an output value at an absolute humidity of 10 g / kg ′ (relative humidity of 20 ° C. and 60% RH).

  When the absolute humidity calculated from the temperature and humidity measured by the temperature and humidity sensor is 5 g / kg ′, there is no sensitivity curve passing through 5 g / kg ′ as shown in FIG. Each point (1), (2), (3)... Of the 5 g / kg 'value of each concentration (1000 ppm, 500 ppm, 200 ppm...) Is proportionally between the sensitivity curves of 3 g / kg ′. Ask. Next, a sensitivity curve of 5 g / kg 'is obtained by connecting the points with straight lines.

  Now, assuming that the output value measured by the semiconductor sensor is 3.8 V, the absolute value of absolute humidity is 10 g / kg ′ (20 ° C. 60% RH) from the point B of 3.8 V of the sensitivity curve A created by the trap. ) Is projected vertically onto the sensitivity curve (solid line) to find point C, and point D (4.2 V) on the voltage axis (vertical axis) can be obtained from point C.

  The interpolation method may be linear interpolation or exponential function. If an exponential function is used, the interpolation accuracy is further improved due to the characteristics of sensor sensitivity.

Next, the effect of temperature and humidity correction will be described with reference to FIGS.
FIG. 3 and FIG. 4 show the time change of the output value of the semiconductor sensor when 20 ppm is injected after injecting 10 ppm of ethanol under conditions where the indoor temperature is 20 ° C. and the relative humidity is 55% and 16%. It is a thing.

  In general, when the temperature and humidity are 20% and 55%, as shown in FIG. 3, the semiconductor sensor shows a normal output. However, in the case of 16% at 20 ° C., as shown in FIG. 4, the output value (dotted line) of the semiconductor sensor shows a value lower than the true value due to the influence of the relative humidity being lowered. In this case, if the temperature / humidity correction according to the present invention is applied, it can be confirmed that the value returns to or approaches the true value as shown by the solid line in FIG.

  In the above embodiment, the drift of the sensor amplifier of the measurement system can be corrected. In general, because the sensor amplifier of the measurement system also has output fluctuation due to temperature, usually a chopper amplifier that is not affected by temperature or a high-precision measurement amplifier that is not easily affected by temperature fluctuation is used. Since temperature and humidity are measured for sensor correction, the temperature drift of the sensor amplifier with respect to temperature and humidity may be measured in advance, and the temperature drift of the sensor amplifier may be corrected by calculation using the measured value.

(Outside air introduction amount control system)
Next, the outside air introduction amount control system according to the present invention will be described.
An outside air introduction amount control system according to the present invention includes the TVOC detection device 10 and the ventilation device described above, and controls the amount of outside air introduced into the room and the ventilation amount by the ventilation device based on the detected value of TVOC by the semiconductor sensor. Is.

  Here, an air conditioner or an air purifier may be further provided, and the operation of the air conditioner or the air purifier may be controlled based on a detection value of a semiconductor sensor or the like.

  In addition, since there are many types of odors that can be perceived by humans, it is difficult to detect all of these odors with a single sensor. Therefore, the outside air introduction amount control system according to the present invention is capable of measuring a plurality of types of odors. The odor sensor may be further provided. Then, the outside air introduction amount and the ventilation amount may be controlled based on the detected odor value by the odor sensor.

  This odor sensor can detect odorous substances such as hydrocarbons (aromatic, fatty, etc.), ketones, aldehydes, alcohols, ethers, lower fats, nitrogen compounds, sulfur compounds and halides. Using a plurality of sensors, covers an odor area that cannot be handled by only one type. When the odor sensor is affected by temperature and humidity, the same correction as the TVOC semiconductor sensor may be performed. In particular, in the odor sensor, the relative humidity may be 70 to 80% or higher and may be higher than the true value. Therefore, the application of the correction method of the present invention is effective.

  In this way, control is performed such as introducing outdoor air or purifying the indoor environment with an air cleaner if the concentration of TVOC or the like in the room exceeds a certain level, or reducing the amount of outside air introduced if the concentration is below a certain level. It is possible to control the amount of outside air introduced and the amount of ventilation in real time. For this reason, the air quality of a living room can always be monitored by TVOC and the level of an odor, and can be maintained in a highly clean state. In addition, by reducing unnecessary ventilation and air conditioning equipment operation, it is possible to save energy and reduce the cost of air conditioning by reducing the outside air load.

(External air introduction control example using odor sensor)
Next, an example of outside air introduction control by the odor sensor will be described with reference to FIG.

  As shown in FIG. 5, for example, when the output value of the odor sensor is 2 V or more, it is determined that odor has occurred, and control is performed to increase the outside air introduction amount to 2 times / h. Note that the normal outside air introduction amount is assumed to be 0.5 times / h.

The output value of the odor sensor can be set for each target substance to be controlled and the conditions of the indoor environment. In some cases, it is possible to set the ventilation (outside air introduction amount) to 20 to 30 m ³ / h · person according to the ratio of the occupants in the room and to increase the outside air introduction amount when necessary.

Further, even when the carbon dioxide (CO ₂ ) sensor is used and the standard concentration of the so-called Building Sanitation Law (Building Management Law) is 1000 ppm or less, if the output value of the odor sensor is 2 V or more, for example, the outside air introduction amount is increased. It is also possible to perform control. Further, when a plurality of odor sensors with different substances to be sensed are used, it is possible to use a selector and control the amount of outside air introduced by the sensor having the highest output value.

  In addition, immediate control to start introduction of outside air as soon as the sensor output value becomes 2V or more, and timer control to introduce outside air after an interval of several seconds to several minutes in order to eliminate the output of sensor noise, etc. Is also possible.

  Further, not only the outside air introduction control but also the operation of the air cleaner and the window ventilation may be controlled based on the sensor output value. Furthermore, monitoring by a sensor may be performed on a composite object such as TVOC and odor, and the above-described control may be performed based on these sensor output values.

  As described above, according to the present invention, a method for detecting the concentration of TVOC in a room using a semiconductor sensor, a sensitivity curve showing the relationship between the concentration of TVOC and the output signal of the semiconductor sensor. Is determined in advance for each absolute humidity, and when detecting the concentration of TVOC in the room with the semiconductor sensor, the temperature and humidity at the position of the semiconductor sensor are simultaneously measured with the temperature and humidity sensor, and the absolute value is determined based on the measured value. The humidity is obtained, the TVOC density corresponding to the output signal of the semiconductor sensor is read from the sensitivity curve corresponding to the absolute humidity, and the output signal corresponding to the read TVOC density is read from the sensitivity curve defined as the true value. Since the output signal is used as a correction value to correct the temperature / humidity error of the output signal of the semiconductor sensor, TVOC can be detected with high accuracy.

  As described above, the TVOC detection method, the detection device, and the outside air introduction amount control system according to the present invention can detect fields where TVOC detection is required in the room (improvement of indoor air quality, maintenance, etc.), and odor detection in the room. It is useful in fields that require a large amount of energy (reduction of indoor odor, etc.), and is particularly suitable for housing, offices, hospitals, health facilities and production facilities.

2 Indoor 10 TVOC detector 12 Semiconductor sensor 14 Temperature / humidity sensor 16 Microcomputer 18 Unit 20, 22 Signal line

Claims (7)

A method for detecting the concentration of TVOC in a room using a semiconductor sensor,
A sensitivity curve indicating the relationship between the TVOC concentration and the output signal of the semiconductor sensor is obtained in advance for each absolute humidity,
When detecting the concentration of TVOC in the room with the semiconductor sensor, the temperature and humidity at the position of the semiconductor sensor are measured simultaneously with the temperature and humidity sensor, and the absolute humidity is obtained based on the measured value and corresponds to the absolute humidity. The TVOC density corresponding to the output signal of the semiconductor sensor is read from the sensitivity curve, the output signal corresponding to the read TVOC density is read from the sensitivity curve defined as a true value, and the output signal is used as a correction value to the semiconductor. A TVOC detection method comprising correcting a temperature / humidity error in an output signal of a sensor.   The TVOC detection method according to claim 1, wherein drift of a sensor amplifier of a measurement system accompanying output fluctuation due to temperature is corrected based on a measurement value of a temperature / humidity sensor. A device that detects the concentration of TVOC in a room using a semiconductor sensor,
A temperature / humidity sensor for measuring the temperature / humidity of the position of the semiconductor sensor at the same time when the concentration of TVOC in the room is detected by the semiconductor sensor;
A microcomputer electrically connected to the semiconductor sensor and the temperature / humidity sensor;
In the memory of the microcomputer, a sensitivity curve indicating the relationship between the concentration of TVOC prepared in advance for each absolute humidity and the output signal of the semiconductor sensor is stored.
The microcomputer obtains the absolute humidity based on the measurement value of the temperature and humidity sensor , reads the TVOC concentration corresponding to the output signal of the semiconductor sensor from the sensitivity curve corresponding to the absolute humidity, and reads the TVOC concentration read The TVOC detection apparatus is characterized in that the output signal corresponding to is read from a sensitivity curve defined as a true value, and the temperature and humidity error of the output signal of the semiconductor sensor is corrected using this output signal as a correction value.   4. The TVOC detection apparatus according to claim 3, wherein the drift of the sensor amplifier of the measurement system accompanying the output fluctuation due to temperature is corrected based on the measurement value of the temperature / humidity sensor.   An outside air introduction amount control system comprising the TVOC detection device according to claim 3, wherein the outside air introduction amount is controlled based on a detected value of the TVOC.   The outside air introduction amount control system according to claim 5, further comprising a plurality of odor sensors for measuring a plurality of types of odors.   The outside air introduction amount control system according to claim 6, wherein the outside air introduction amount is controlled based on a detected value of odor.

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