JP6515317B2 - Particle detector - Google Patents

Description

  The present invention relates to a particulate matter detection device for measuring the amount of dust contained in air used to determine the state of fine dust contamination of air.

  In recent years, the health problems associated with pollen, allergic house dust, and fine dust in the air, represented by PM2.5, are socially expanding. In order to cope with such problems, it is effective to use an air conditioner such as an air purifier that keeps clean air quality by collecting dust in the air.

  However, in air cleaners and the like, it is desirable to automatically operate according to the occurrence of dust from the viewpoint of energy saving and convenience, and it is desirable to perform automatic operation more optimally according to the amount of dust in the air. ing.

  The type of dust can be identified because it is necessary to control the amount and direction of air blowing according to the type and amount of dust present in the air for optimum automatic operation such as this air cleaner. There is a growing demand for detection methods.

  As a method of identifying the type of such dust, a method of identifying and determining the difference in particle diameter of the particles constituting the detected dust is widely used. Although this method is inferior in accuracy, it can be realized at low cost because of its relatively simple configuration.

  Heretofore, there has been known a method of detecting this type of particle detecting device based on the difference in the intensity of scattered reflected light due to the dust of the irradiated light (see, for example, Patent Document 1).

  The particle detector will be described below with reference to FIG.

  As shown in FIG. 7, the conventional particle detector comprises an LED light emitting circuit 101 for irradiating light to dust 100 floating in the air, a dust detector 102 for detecting dust in the air and outputting a pulse signal. The microcomputer 103 is configured to determine the contamination state of air from the difference in the quantity by reading the pulse signal.

  The dust detector 102 includes a light receiving circuit 104, an amplification circuit 105, a particle diameter determination circuit 106, and an output circuit 107. The light receiving circuit 104 receives the reflected light that becomes higher in intensity as the particle diameter of the dust 100 is larger, and outputs a voltage signal according to the light receiving intensity. The light receiving circuit 104 is a main component of the dust detector 102 and is a light receiving element. The amplifier circuit 105 amplifies the voltage signal. The particle diameter determination circuit 106 is composed of a comparator, and converts the amplified voltage signal into a pulse signal by comparing it with a voltage threshold serving as a determination reference value that defines the voltage signal, and outputs the pulse signal. The output circuit 107 amplifies the output pulse signal into a change in a prescribed voltage value that can be read by the microcomputer 103.

  Further, a level switching circuit 108 for switching the voltage threshold of the particle diameter determination circuit 106 by the microcomputer 103 is provided. The level switching circuit 108 provides the voltage threshold of the particle diameter determination circuit 106 in two stages, and the microcomputer 103 switches the voltage threshold alternately. In this manner, one dust detector 102 can determine a plurality of dust amounts having different particle diameters.

  In addition, although a specific case is not shown, this type of particle detector includes at least one set of a particle diameter determination circuit 106 in which different voltage thresholds are previously set in the dust detector 102, and an output circuit 107. In some cases, the amount of dust having different particle diameters can be determined by reading the corresponding pulse signal output by the microcomputer 103.

Patent No. 3894752

  In such a conventional particle detection device, the voltage of two stages of the particle diameter determination circuit 106 is set by the microcomputer 103 via the level switching circuit 108, with the LED light emitting circuit 101 as a light emitting element and the light receiving circuit 104 as one set. The pulse signal output from the dust detector 102 is read while switching the threshold value. In this manner, a plurality of types of dust having different particle diameters of two types are determined.

  Further, the dust detector 102 is provided with one or more sets of particle diameter determination circuit 106 in which different voltage threshold values are set in advance, and output circuit 107, and the microcomputer 103 reads the corresponding pulse signals to be output. It was configured to determine a plurality of different dust amounts.

  Therefore, it is basic to determine the amount of dust with different particle diameters based on the difference in voltage value of the voltage signal obtained from the combination of one set of light emitting element and light receiving element, and the determination result of the amount of dust on the small particle diameter side Has the problem that the influence of the amount of dust of the large particle diameter adjacent to is also included.

  Therefore, the present invention solves the above-described conventional problems, and is configured to obtain a plurality of pulse signals with different particle diameters from voltage signals obtained from a combination of a light emitting element and a light receiving element to determine the amount of dust. An object of the present invention is to provide a particulate matter detection device capable of more accurately determining the amount of dust on the small particle diameter side in the relationship between adjacent small particle diameters and large particle diameters.

And in order to achieve this object, according to the present invention, based on the intensity of the reflected light due to the scattering of the irradiation light, a pulse-like detection signal having a time width corresponding to a plurality of particle sizes of dust present in the air A particulate detection apparatus comprising: a particulate detection means for outputting; and a determination means for reading the detection signal and determining the dust amount of the corresponding particle diameter from the generation amount of the signal per unit time, wherein the determination means detects the read among the signals, it subtracts the detection signal indicating the larger particle diameter from the detection signal indicating the small particle diameter when the detection signal indicating the detection signal and the large particle size shows a small particle size has been detected at the same time, the small particle size To determine the amount of dust, thereby achieving the desired purpose.

According to the present invention, there is provided the particle detecting means for outputting a pulse-like detection signal having a time width corresponding to the plurality of particle diameters of the dust present in the air based on the intensity of the reflected light due to the scattering of the irradiation light In the particulate matter detection apparatus comprising a determination means for reading the detection signal and determining the dust amount of the corresponding particle size from the generation amount of the signal per unit time, the determination means comprises the small particle size of the read detection signal. When the detection signal indicating the large particle size is detected simultaneously with the detection signal indicating the small particle size , the detection signal indicating the large particle size is subtracted from the detection signal indicating the small particle size to determine the amount of dust of the small particle size Since the determination means determines the amount of dust of the small particle diameter based on the difference between the small particle diameter read and the large particle diameter detection signal, the influence on the large particle diameter side is suppressed.

Block diagram showing a schematic configuration of the particle detector of the first embodiment of the present invention A circuit diagram showing a schematic circuit structure of the same particle detection means The block diagram which shows the general | schematic structure of the said microparticles | fine-particles detection means Chart showing details of generation of detection signal output from the same particle detection means A chart showing the temporal change of the detection signal for explaining the method of determining the amount of dust on the small particle diameter side based on the difference between the detection signals A chart showing the temporal change of the detection signal for explaining another method of determining the amount of dust on the small particle diameter side based on the difference between the detection signals Block diagram showing a schematic circuit configuration of a conventional particle detector

The particulate matter detection apparatus according to claim 1 of the present invention outputs a pulse-like detection signal having a time width corresponding to a plurality of particle sizes of dust present in the air based on the intensity of the reflected light due to the scattering of the irradiation light. In the particle detector including the particle detection means for determining and the determination means for reading the detection signal and determining the dust amount of the corresponding particle diameter from the generation amount of the signal per unit time, the determination means of subtracts the detection signal indicating the larger particle diameter from the detection signal indicating the small particle diameter when the detection signal indicating the detection signal and the large particle size shows a small particle diameter are simultaneously detected in the small particle size dust effect of the large particle size side in order to determine the amount is suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1
As shown in FIGS. 1 and 2, the particulate matter detection device according to the present embodiment has a pulse-like voltage according to the size of dust present in the air, based on the intensity of the reflected light due to the scattering of the irradiated light. A particle detection means 1 for outputting a signal, and a determination means 2 for reading the voltage signal and determining the amount of dust in the air from the amount of generation of the signal per unit time are constituted.

  The particulate detection means 1 comprises a light emitting means 3, a light receiving means 4 and a signal conversion means 5. The light emitting means 3 irradiates light to the fine particles 6 constituting fine dust only in the air. The light receiving means 4 receives the light emitted from the light emitting means 3 which is scattered and reflected on the surface of the fine particle 6, and outputs a voltage signal according to the light receiving intensity. The signal conversion means 5 amplifies the voltage signal to a manageable voltage level, converts it into a pulse-like rectangular waveform signal, and outputs it.

  The signal conversion means 5 comprises an amplification means 7, a comparison means 8 and a voltage conversion means 9. The amplifying means 7 amplifies the voltage signal output from the light receiving means 4 to a manageable voltage level. The comparison means 8a and 8b convert the voltage signal amplified by the amplification means 7 into a pulse-like rectangular waveform signal by comparing it with voltage threshold values as two determination reference values defining the signal and output it. The voltage conversion means 9a, 9b convert the output signal into a voltage value that can be read by the determination means 2 to output a detection signal as a pulse-like voltage signal, and the comparison means 8a, 9b, It corresponds to each 8b.

  The determination means 2 is provided with input terminals 10a and 10b, and a detection signal output from the particle detection means 1 is read into the inside.

  Further, the particle detection means 1 and the determination means 2 are operated by the power supplied from the power supply means 11.

  Here, in the present embodiment, the comparison means 8a and 8b are described as providing voltage thresholds serving as two judgment reference values, but the number of these means is not particularly limited, and two or more kinds are provided. A plurality of means provided with a voltage threshold may be provided.

  The voltage threshold provided in the comparison means 8a, 8b corresponds to the setting of the particle diameter of the dust to be detected as will be described later.

  Here, the determination means 2 uses, for example, a microcomputer of one chip.

  This microcomputer integrates a central processing unit for performing calculation and determination processing, an input / output terminal, an A / D input terminal, a read only memory, a random access memory, and the like. The input / output terminal takes in and outputs an external voltage change signal. The A / D input terminal converts an analog voltage signal into a digital value and takes it in. The read only memory stores operation procedures as software. The random access memory is for temporarily storing operation and judgment states.

  In the judging means 2 constituted by such a microcomputer, an electric signal consisting of a change of the Hi potential or the Lo potential or an analog voltage value is read into the microcomputer as a digital value at the input terminal 10. The Hi potential is the voltage potential of the drive power supply defined by the specification of the electrical signal of the allowable voltage. The Lo potential is a reference potential (GND).

  Also, it is stored as a procedure of a series of control processing on a read only memory as a program of software description, and this procedure is made in accordance with a prescribed timing or based on the change of digital value of the electrical signal read inside. Execution can execute required control operations.

  Here, the light emitting means 3 is composed of a circuit mainly composed of a light emitting diode which emits light with high efficiency if a constant direct current flows. The light emitting means 3 preferably has a configuration using a light emitting diode other than visible light, for example, emitting infrared light, in order to suppress the influence of the incident of the external visible light which interferes with the determination of the accurate value of the amount of dust. .

  In addition, the light emitted from the light emitting means 3 is scattered on the surface of the fine particles 6 to become minute reflected light. Therefore, the light receiving means 4 can receive minute reflected light, efficiently convert it into a voltage signal according to the light reception intensity, and can output it. For example, the circuit is mainly composed of a photodiode. Furthermore, when using the light emission means 3 of infrared light emission, the structure using the photodiode of infrared light reception provided with the optical filter which suppressed the permeability | transmittance other than infrared light is desirable.

  Moreover, the light receiving means 4 can also use the phototransistor which is light receiving elements other than a photodiode as a main structure.

  Note that FIG. 3 shows a schematic structural view around the light emitting means 3 and the light receiving means 4. The light emitting means 3 and the light receiving means 4 fix their arrangement positions and are housed inside the outer shell member 12. The outer shell member 12 has a structure for preventing the incidence of ambient light while securing a flow of air so as to take in the fine particles 6 of dust from the ambient.

  Further, as shown in the figure, in order to prevent the radiation light from the light emitting means 3 from being directly incident on the light receiving means 4, the light axis and the light axis center in the incident direction cross each other. Place and fix so that the optical axes intersect at about 80 ° to 140 °.

  The point at which the optical axes intersect is the dust detection point 13.

  In addition, it is also common to arrange the lens 14a for making it reinforce by condensing the radiation light from the light emission means 3 with respect to this detection point 13. FIG.

  This makes it possible to detect finer dust by increasing the reflection luminance from finer particles.

  Furthermore, the lens 14b may be arranged so that only the reflected light from the detection point 13 is selectively incident on the light receiving means 4 in the same manner.

  Here, the amplifying means 7 does not require a specific specification, and is constituted by a circuit mainly composed of a general DC type operational amplifier (op-amp) for amplifying a minute voltage signal to a required voltage. is there.

  Also, the comparison means 8a and 8b do not obtain a specific specification, but generally convert it into a pulse-like voltage signal by comparing it with a voltage threshold which is a determination reference value defining an input voltage signal. Comparator is composed mainly of a circuit.

  The voltage conversion means 9 converts the input pulse-like voltage signal into a signal of a voltage value permitted to the input terminal 10 of the microcomputer serving as the determination means 2. For example, it is configured by a switch circuit using a simple transistor element.

  According to such a configuration, as the particle diameter of the dust to be detected is larger, the time for crossing the detection point 13 is longer, and the reflected light is also increased. Therefore, the voltage signal output from the light receiving means 4 also has a longer duration and a larger voltage value as the particle diameter is larger. Therefore, the width of the pulse-shaped detection signal output from the particle detection means 1 changes in accordance with the particle diameter of the dust. That is, as the particle diameter of the dust is larger, the width of the detection signal output from the particle detection means 1 is wider. In addition, when the particle size of the dust decreases, the width of the detection signal output from the particle detection means 1 narrows.

  The comparison means 8a, 8b and the voltage conversion means 9a, 9b are not absolutely required. For example, the pulsed voltage signal output from the comparison means 8 is less than or equal to the voltage value permitted to the input terminal 10 of the microcomputer constituting the determination means 2, and the Hi potential can be determined by the microcomputer as a detection signal. If it is within the range of the change of the voltage value between the Lo potential and the change of the analog voltage value, the voltage conversion means 9 can be omitted.

  Similarly, the amplified voltage signal output from the signal conversion means 5 is equal to or less than the voltage value permitted to the input terminal 10 of the microcomputer constituting the determination means 2 and an analog voltage value that can be determined as a detection signal by the microcomputer The comparison means 8 can also be omitted if it is within the range of change.

  Here, the power supply means 11 supplies stabilized direct current power.

  For example, after alternating current voltage is rectified using an AC high voltage commercial power supply as an electric power supply source and then intermittent current is conducted to the primary side of the transformer to generate a stepped-down voltage on the secondary side of the transformer, then rectified and generated. It is possible to use a so-called switching regulator circuit configuration that stabilizes and outputs a voltage of a specified value by feeding back the value of the same DC voltage and changing the period and interval of the intermittent current compared with the reference voltage. .

  Further, a storage battery such as a battery may be used which supplies electric power for a fixed time to the load side at a voltage of a specified value by storing electric charge.

  Although the particle detecting means 1 and the judging means 2 have been described so far as to operate by supplying a stable voltage from one power supply means 11, they may operate with different stable voltages, It does not prescribe.

  As described above, the power supply unit 11 is not limited as long as it can supply stabilized direct current power, and the configuration thereof is not related to the gist of the present embodiment, and thus the detailed description will be omitted.

  As described above, the width of the detection signal output from the particle detection means 1 becomes wider as the particle size of the target dust becomes larger, and basically corresponds to the particle size of the dust.

  However, if the speed of the dust moving through the detection point 13 described above is increased, the light reflection time is shortened even for dust of the same particle diameter, and the width of the resultant voltage signal is also narrowed. Become. Therefore, for reproducible detection, it is necessary to control the dust to move the detection point 13 at a constant speed.

  Therefore, a blower mechanism is generally provided to generate a flow of air at a constant speed in a fixed direction at the detection point 13 from the periphery of the shell member 12.

  As this air blowing mechanism, it is general to use, for example, an air blower for generating a flow of wind with a constant wind velocity, or thermal convection based on an electric heating element as a device for moving the fine particles 6 in the vertical direction. The detailed description is omitted because it is not related to the abstract.

  Next, details of generation of a detection signal output from the particle detection means 1 will be described using a graph shown in FIG.

In FIG. 4, the voltage signal (Vs in the figure) output from the light receiving means 4 and amplified by the amplifying means 7 is compared with the voltage by the comparing means 8a and 8b and voltage converted by the voltage converting means 9a and 9b. The voltage values of detection signals (Vpa and Vpb in the figure) output as voltage-like voltage signals are taken on the vertical axis, and time is placed on the horizontal axis to show the state of change in each signal with respect to the progress of time. . The state in which V _L shown in the detection signal of FIG. 4 is output is the state in which the particulate matter detection means 1 detects dust.

  As described above, the voltage signal output from the light receiving means 4 also has a longer duration and a larger voltage value as the particle diameter is larger. From this, even in the voltage signal Vs amplified by the amplification means 7, the change in each voltage rising in a pulse shape indicates a state in which the particle is detected, and the larger the pulse width and the higher the voltage value, the larger particle diameter It shows that the dust which becomes

Therefore, if voltage comparisons (Vta and Vtb in the figure) are made that provide two determination reference values that define the amplified voltage signals in comparison means 8a and 8b, voltage comparison is performed according to each of voltage thresholds Vta and Vtb. The generation of a voltage signal of a certain level or more can be known as generation of a detection signal which is a pulse-like rectangular waveform. This indicates that if the voltage threshold values in the comparison means 8a and 8b are appropriately selected, detection of dust having a particle diameter larger than each constant particle diameter can be determined by the presence or absence of the output of the detection signals Vpa and Vpb. As the voltage value of the amplified voltage signal increases as the particle diameter increases, the voltage threshold Vtb on the high voltage side shown in the figure is for determining dust with a particle diameter larger than the voltage threshold Vta. It turns out that it becomes setting. Therefore, the detection signal Vpa and the detection signal Vpb determined by the setting of the two voltage thresholds Vta and Vtb correspond to the detection results of the small particle diameter and the large particle diameter dust.

  Also, as shown in the figure, the pulse width of the detection signal generated changes depending on the magnitude (voltage value or duration) of the amplified voltage signal. This indicates that when dust having a particle diameter causing a voltage signal exceeding each voltage threshold is detected, the difference in the particle diameter appears as a difference in the pulse width of the detection signal. Therefore, if a certain unit time is defined, and the total number and occupied time ratio of each detection signal per unit time are determined, each particle diameter defined by the voltage threshold value of the particles 6 contained in the dust present in the surrounding air The amount of dust can be determined.

  The specified time width is determined experimentally, and for example, a detection signal obtained when the particle detection means 1 to be utilized is disposed in a test space in which test particles of a fixed particle diameter are dispersed. The average value of the width of is determined and specified. That is, the particle diameter of the test particles at this time corresponds to the particle diameter of the dust to be determined. Similarly, the voltage threshold value defined by each of the comparison means 8a and 8b also sets the voltage value at which the pulse of the detection signal is obtained when arranged in the above-mentioned test space, and the particle diameter of the test particle at this time. Is the particle diameter of the detection target. Furthermore, the relationship of the total amount of dust to unit time is also determined experimentally. For example, when the particle detection means 1 to be studied is disposed in the above-mentioned test space, the amount and frequency of generation of detection signals and dust obtained per defined unit time (for example, arbitrary time from several seconds to several minutes) It is determined by changing the amount of test particles to disperse the relationship with the amount of dust (count number and weight conversion value per unit volume) present in air measured by a measuring instrument or the like.

  Here, the detection signals Vpa and Vpb output from the particle detection means 1 are the voltage comparison of one voltage signal Vs amplified by the amplification means 7 with the two voltage threshold values Vta and Vtb as described with reference to FIG. Is obtained as a result.

Therefore, if the detection signal Vpb corresponding to the large particle diameter side is in the detection state (a state in which the detection signal outputs V _L , hereinafter V _L state), the detection signal Vpa corresponding to the small particle diameter side is also detected simultaneously Indicates that a signal is output as a state (V _L state).

This means that even when the detection signal Vpa is in the detection state (V _L state), dust with a large particle diameter is detected simultaneously when the detection signal V pb is in the detection state (V _L state), or small particles having a large particle diameter It suggests that finer dust of the diameter may be detected overlapping.

  Therefore, if the amount of dust is determined including the detection signals Vpa and Vpb simultaneously in the detection state, the amount of dust of the large particle diameter naturally influences the determination result on the small particle diameter side, and the accuracy may be lowered as a result There is sex.

  Therefore, when determining the amount of dust with a small particle diameter, more accurate judgment can be made by subtracting the influence of the detection state of the detection signal Vpb on the large particle diameter side from the detection signal Vpa on the small particle diameter side. I understand that.

Next, when the amount of dust on the small particle diameter side is determined using the graphs shown in FIG. 5 and FIG. 6, the method of the process performed in the determination means 2 for determining the difference between the small particle diameter and the large particle diameter detection signal Explain.

In FIGS. 5 and 6, each voltage value of the detection signal (Vpa, Vpb in the figure) outputted from the particle detection means 1 is taken as the vertical axis and time is arranged on the horizontal axis, Only the state of change is extracted and shown. The detection signal shown in FIGS. 5 and 6 is also outputting the V _L when the particle detection means 1 detects dust.

For example, as shown in FIG. 5, if the detection signal Vpa and the detection signal Vpb are simultaneously in the detection state (V _L state) as shown in FIG. The upper Vs1) is determined, and the amount of dust on the small particle diameter side is determined based on the detection signal Vs1.

The same method is based on the idea that if the detection signal Vpa and the detection signal Vpb are simultaneously in the detection state (V _L state), it is determined that only dust with a large particle diameter is detected.

  However, the possibility that the large particle size is overlapped with the small particle size dust is out of consideration, and there is a concern that the amount of the small particle size dust obtained as a result is determined to be smaller.

From this, for example, as shown in FIG. 6, when the detection signal Vpa and the detection signal Vpb are simultaneously in the detection state (V _L state), the width of the detection pulse of the detection signal Vpb is subtracted from the detection pulse of the detection signal Vpa It is also conceivable to determine a new detection signal (Vs2 in the drawing) and determine the amount of dust on the small particle diameter side based on the detection signal Vs2.

  If the detection signal Vs2 is determined, the detection pulse width of the detection signal Vpa can be reduced to reflect the influence of the possibility that the large particle diameter is overlapped with the small particle diameter dust.

  Whether the method of obtaining the detection signal Vs1 or the method of obtaining the detection signal Vs2 can be used to determine the dust amount on the small particle diameter side more accurately depends on the difference between the particle detection means 1 used and the air contamination to be targeted This is a case-by-case case due to the difference in the particle size distribution of dust (in which the content is large on the large particle size side or more).

  Therefore, in practical use, it is necessary to select a processing method for obtaining a difference by which the amount of dust on the small particle diameter side with high accuracy can be determined based on the actual measurement results.

  The above description is based on the case where the signal conversion means 5 of the particle detection means 1 is provided with a plurality of comparison means 8 and voltage conversion means 9 and detection signals according to a plurality of particle sizes are outputted from the particle detection means 1 The

  However, as described above, the comparison means 8 is not mounted on the signal conversion means 5 of the particle detection means 1 and one voltage signal amplified by the amplification means 7 is changed as a change in analog voltage value by the microcomputer serving as the determination means 2 It is also possible to determine the read dust amount.

  As described above, in the method of reading a voltage signal as a change in analog voltage value, a plurality of voltage threshold values are defined as digital values, each detection signal corresponding to each voltage threshold value is determined by software processing, and further differential processing If you

According to such a configuration, the particulate matter detection means 1 which outputs a pulse-like detection signal having a time width corresponding to a plurality of particle sizes of dust present in the air based on the intensity of the reflected light due to the scattering of the irradiation light. Even in this case, the detection signal is read by the judging means 2, and the amount of dust on the small particle diameter side is judged based on the difference between the small particle diameter and the large particle diameter of the read detection signal. Therefore, since the influence of the large particle system can be suppressed in the determination of the amount of dust on the small particle diameter side, the amount of dust on the small particle diameter side can be determined more accurately.

Particle detecting apparatus according to the present invention, the apparatus having to detect dust quantity according to a plurality of the particle diameter of the dust present in the air based on the intensity of the reflected light due to scattering of the irradiating light, large from the small particle size Since the influence of the large particle system can be suppressed by determining the amount of dust on the small particle diameter side based on the difference in particle diameter, it is useful as a particulate detection device etc. that can more accurately determine the amount of dust on the small particle diameter side. .

1 particle detection means 2 determination means

Claims (2)

Particle detection means for outputting a pulse-like detection signal having a time width corresponding to a plurality of particle sizes of dust present in the air based on the intensity of the reflected light due to the scattering of the irradiation light;
A particle detector comprising reading means for reading the detection signal and determining the amount of dust of the corresponding particle size from the amount of signal generation per unit time,
The determination means of the read detection signal, the detection signal indicating the larger particle diameter from the detection signal indicating the small particle diameter when the detection signal indicating the detection signal and the large particle size shows a small particle size has been detected at the same time A particulate matter detecting device characterized by subtracting the amount of dust of small particle diameter by subtracting. Particle detection means for outputting a pulse-like detection signal having a time width corresponding to a plurality of particle sizes of dust present in the air based on the intensity of the reflected light due to the scattering of the irradiation light;
A particle detector comprising reading means for reading the detection signal and determining the amount of dust of the corresponding particle size from the amount of signal generation per unit time,
The determination means of the read detection signal, the small particle size except a detection signal indicating the small particle diameter consecutive in the case where the detection signal indicating the detection signal and the large particle size shows a small particle size has been detected at the same time What is claimed is: 1. A particulate matter detection device characterized by determining the amount of dust.

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