JP3543496B2 - Odor detection device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an odor detection device that is used for quality inspection of food and the like and detects an odor substance and the like in the atmosphere.
[0002]
[Prior art]
In recent years, research has been conducted using a conductive polymer film that is sensitive to a specific substance in a sample gas as an odor sensor.Currently, an odor sensor that uses a change in the resistance value of a metal oxide semiconductor or a conductive polymer is used. Odor sensor having a structure in which a lipid film or an organic film containing a sensitive substance is attached to a quartz oscillator, and an odor sensor having a structure in which the sensitive film is attached to a SAW device. Has been put to practical use.
[0003]
Then, a quality inspection device for controlling the quality of food by detecting a substance component in a sample gas serving as a base of the odor by the odor detection device is being widely developed.
[0004]
[Problems to be solved by the invention]
However, since the above-mentioned odor detection devices are all too low in sensitivity compared to the odor of living things such as human and dog nose, for example, when used for food inspection, etc. There was a problem that it could not be completely detected and that sufficient quality control could not be achieved.
[0005]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a highly sensitive odor detection device that can withstand quality control such as food inspection.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an odor detection device according to the present invention includes an odor sensor that outputs a unique signal corresponding to an odor substance, adsorption / desorption means for adsorbing / desorbing a sample gas, and desorption by the adsorption / desorption means. Flow path means for guiding the extracted gas to the odor sensor.
[0007]
The odor sensor is characterized by comprising a conductive polymer film such as PAT6 (polyalkylthiophene), polypyrrole, PTMSiPA, CNPPV or the like.
[0008]
The adsorbing and desorbing means comprises an adsorbent such as a porous polymer bead, and a means for allowing an odorless gas to pass through the adsorbent.The adsorbent adsorbs an odorous substance in the sample gas, separately from the sample gas. It is characterized in that adsorbed odor substances are desorbed by passing odorless gas.
[0009]
At the time of desorption, it is preferable to use a heating means for heating the adsorbent in order to increase the desorption efficiency.
[0010]
The present invention provides an odor sensor that outputs a unique signal according to an odor substance, adsorption / desorption means for adsorbing / desorbing a sample gas, and a flow path means for guiding the gas desorbed by the adsorption / desorption means to the odor sensor. And a control means for giving an instruction to the adsorption / desorption means so as to desorb the adsorbed gas after adsorbing the sample gas for a predetermined time.
[0011]
Further, the present invention relates to an odor detection device provided with or without the control means, on a flow path for guiding a sample gas to the adsorption / desorption means or a flow path for guiding the gas desorbed by the adsorption / desorption means to the odor sensor. It can also be configured as an odor detection device provided with a moisture adsorption means on the means.
[0012]
The moisture adsorbing means is made of activated alumina, zeolite, and silica gel.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an external view of an odor detection device according to an embodiment of the present invention. Sample gas sucked from an inlet 10 is taken into a main body through a filter 5 to detect odor, and then discharged from an outlet 12. The air suction port 11 for supplying air to the odor removing section inside the main body is separately provided.
[0014]
FIG. 2 is a configuration diagram of an odor detection device according to one embodiment of the present invention. In a sample gas sucked from an inlet 10, dust and the like are removed by a filter 5, and a switching valve 4 b is switched through a flow path a. Is supplied to any of the channels b, c, and i.
[0015]
The flow path i is provided with a water removing section 6, an adsorbing / desorbing section 1 and a heater 1a. The water removing section 6 has a water absorbing substance such as activated alumina, zeolite, silica gel or the like inside. In addition, the adsorption / desorption section 1 has a porous polymer bead for adsorbing an odorant inside. For example, a commercially available porous polymer bead such as “Tenax GC” can be used. It is preferably used for the adsorption / desorption section 1 because of its excellent adsorbing property and the excellent effect of removing moisture affecting the output of the odor sensor section 2 from the adsorbed gas.
[0016]
The heater 1a is disposed close to the adsorbing / desorbing unit 1 so as to heat the adsorbing / desorbing unit 1, and the heating state is controlled by the computer 9, so that the gas adsorbed on the adsorbing / desorbing unit 1 is used to enhance the desorption effect. Through such adsorption and desorption operations, the odor substance in the sample gas can be supplied to the odor sensor section 2 in a concentrated state, and the detection sensitivity of the odor substance is dramatically improved.
[0017]
An odor sensor section 2 is provided in the channel c. The odor sensor section 2 is formed of one or more conductive polymer films such as PAT6 (polyalkylthiophene), polypyrrole, PTMSiPA, and CNPPV. Indicates a resistance change according to the odor substance in the gas, and enables output of a detection signal according to the odor substance.
[0018]
The operation of each of the switching valves 4a to 4d is controlled by the computer 9, and their switching patterns are as shown in FIG. That is, the switching valve 4a switches between two patterns of (flow path d-flow path e) and (flow path d-flow path b), and the switching valve 4b switches (flow path i-flow path c) and (flow The switching valve 4c switches between three patterns of the flow path a-flow path i, the flow path b-flow path c), and the flow path b-flow path i, c. The switching valve 4d switches between two patterns (flow path i-flow path h) and (flow path g-f flow path h). Each is configured to do so.
[0019]
An odor removing unit 3 having activated carbon therein is disposed in the flow path d. The odor removing unit 3 takes in external air from an air intake port 11 and sends it to the odor sensor unit 2 and the adsorption / desorption unit 1 as an odorless gas.
[0020]
Flow velocity controllers 8a and 8b are disposed in the flow path g, and a pump 7 is disposed in the flow path h. The pump 7 serves as a power source for sucking sample gas or the like into the inside from the suction port 10 or the air suction port 11, and the sucked gas is finally discharged to the outside from the discharge port 12.
[0021]
The computer 9 functions as a control unit for performing switching control of the switching valves 4a to 4d and heating control of the heater 1a, and a data processing unit for analyzing a detection signal output from the odor sensor unit 2 and specifying an odor substance. As a function.
[0022]
Next, the operation of the present invention will be described with reference to the flowchart of FIG. 3 showing the operation of the computer 9 and the diagram showing the switching mode of FIG.
[0023]
First, prior to the measurement, the computer 9 sets the apparatus in an idling mode (S1) and waits for a measurement command to be input (S2). The measurement command is an instruction given to the computer 9 by a measurer from a switch (not shown) or the like.
[0024]
Here, in the idling mode, as shown in the upper left column of FIG. 4, the switching valves 4a to 4d are switched, and the heater 1a is in an off state. In this state, the heater 1a has passed the odor removing unit 3 in FIG. The odorless air is supplied to the odor sensor unit 2 through the channels d and e, the adsorption / desorption unit 1 and the water removing unit 6, and is discharged from the outlet 12 through the channels g and h. In such a case, the odorless air from which moisture is removed in the adsorption / desorption section 1 and the moisture removal section 6 is supplied, so that the output of the odor sensor section 2 becomes zero.
[0025]
Next, when the computer 9 detects the measurement command, the computer 9 sets the state of the sampling mode for sucking the sampling gas (S2).
[0026]
Here, in the sampling mode, as shown in the lower left column of FIG. 4, the switching valves 4a to 4d are switched, and the heater 1a is in the off state, and the odorless air that has passed through the odor removing unit 3 flows through the flow path d. , B, and c, the sampling gas sucked in from the suction port 10 while the dust or the like is removed by the filter 5 is then removed by the water removing section through the flow paths a and i. After the water is removed at 6 and the odorant is further adsorbed at the adsorption / desorption section 1, it is discharged from the discharge port 12 through the flow paths f and h.
[0027]
Then, the computer 9 waits until the gas is sufficiently adsorbed on the adsorption / desorption section 1 (S4), and sets the state of the measurement mode 1 (S5). The time required for the odor substance in the sample gas to be sufficiently adsorbed to the adsorption / desorption section 1 is determined by adsorbing a standard gas of a known concentration by changing the adsorption time one by one, and measuring the concentration of the desorbed gas. It is determined by measuring the adsorption time when the concentration is saturated.
[0028]
Here, the measurement mode 1 shows a state where the switching valves 4a to 4d are switched as shown in the upper right column of FIG. 4 (the same as in the idling mode described above) and the heater 1a is turned on. In this state, the odorless air that has passed through the odor removing section 3 is supplied to the odor sensor section 2 through the flow paths d and e, the adsorption / desorption section 1 and the moisture removing section 6, and is supplied through the flow paths g and h. It is discharged from the discharge port 12. At this time, the odor substance adsorbed by the adsorption / desorption section 1 is desorbed by the passage of odorless air and is supplied to the odor sensor section 2, so that the odor sensor section 2 removes the odor substance contained in the adsorbed gas. The corresponding detection signal is output. The desorption of the adsorbed gas from the adsorption / desorption section 1 is promoted by the heating action of the heater 1a.
[0029]
In such a case, since the gas desorbed from the adsorption / desorption section 1 contains the odor substance in the sampling gas sucked in the sampling mode in a concentrated state, the odor sensor section 2 detects the odor substance in the sampling gas. Can be detected at a very high concentration, and as a result, the detection sensitivity is improved.
[0030]
Next, the computer 9 inputs a detection signal from the odor sensor unit 2 and performs odor analysis by performing predetermined data processing to specify odor substances contained in the sampling gas (S6). The identification of the odor substance is performed by previously storing signals from the respective odor sensor units 2 based on various standard gases, and comparing a detection signal obtained in actual measurement with the stored signal. It is done by things. These calculations may use a so-called neural network, which is one of the multivariable analysis methods when outputs from a plurality of sensors are nonlinear.
[0031]
When the odor analysis is completed, the computer 9 sets the state of the measurement mode 2 for measuring the time or speed at which the odor substance adsorbed on the odor sensor section 2 is desorbed (S7).
Here, in the measurement mode 2, the switching valves 4a to 4d are switched as shown in the lower right column of FIG. 4 and the heater 1a is turned off. In this state, the odorless air passing through the odor removing unit 3 is displayed. Is supplied to the odor sensor section 2 through the flow paths d, b, and c, and is supplied to the adsorption / desorption section 1 through the flow paths d, b, and i.
[0032]
In the measurement mode 2, the computer 9 waits for the detection output of the odor sensor unit 2 to become zero, and judges that the odor material has completely desorbed from the odor sensor unit 2 when the detection output becomes zero. The mode shifts again to the idling mode (S8).
[0033]
In the measurement mode 2 described above, since the odorless air that has passed through the odor removing unit 3 passes through the adsorbing / desorbing unit 1, the adsorbent in the adsorbing / desorbing unit 1 can also be refreshed.
[0034]
Then, by repeating the above-described operations of S1 to S8, continuous odor detection in the sampling gas can be performed.
[0035]
【The invention's effect】
According to the present invention, the odor substance in the sampling gas is adsorbed for a certain period of time, and the odor substance in the desorbed gas is configured to be measured, so that highly sensitive odor detection is possible. High quality control of the system is possible.
[Brief description of the drawings]
FIG. 1 is an external view of an odor detection device according to the present invention.
FIG. 2 is an internal structure diagram of the odor detection device according to the present invention.
FIG. 3 is a flowchart showing the operation of the present invention.
FIG. 4 is a diagram showing setting states of a switching valve and a heater in each mode.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Suction part 2 Odor sensor part 3 Odor removal part 4a-4d Switching valve 5 Filter 6 Water removal part 7 Pump 8a, 8b
9 Computer a-i channel

Claims (1)

An odor sensor that outputs a unique signal according to an odor substance, adsorption / desorption means for adsorbing / desorbing a sample gas, and a flow path means for guiding the gas desorbed by the adsorption / desorption means to the odor sensor, An odor detection device, characterized in that:

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