JP2007086064A - Particle detector and particle detecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly determine a suspended particle amount without generating a delay, while adopting an inexpensive binary output type particle sensor. <P>SOLUTION: A particle detector includes particle detecting means 3-7 for outputting an output in response to a photoreception quantity varied based on an influence of scattered light by a suspended particle in the air existing in an optical path, when receiving light emitted from a light emitting element by a photoreception element, a signal determination means 5 for determining the propriety of a high or low level by comparing the outputs from the particle detecting means 3-7 with a preset threshold value, a storage means 13 for storing determination results in the signal determination means 5 respectively in a prescribed detection time unit while delaying a time, a computing means 10 for computing sequentially an output time ratio of the high or low level, based on the determination results stored in the storage means 13 in the respective detection time units, and a particle amount determination means 10 for determining the suspended particle amount, based on the output time ratio computed by the computing means 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a particle detection device and a particle detection method that are employed in an air conditioner such as an air conditioner or an air cleaner having an air cleaning function.

  In general, an air conditioner such as an air conditioner having an air cleaning function or an air purifier is provided with a particle detecting device for detecting particles floating in the air.

  2. Description of the Related Art Conventionally, as a particle detection device, there is one provided with an odor sensor for detecting particles having a small particle diameter such as cigarette smoke and an optical sensor for detecting particles having a large particle diameter such as pollen.

  As another particle detector, an optical particle sensor that irradiates air with light and receives scattered light from suspended particles, and measures the amount of suspended particles from a voltage that changes based on the intensity of the received scattered light. In addition, there is one that detects particles having different particle diameters such as cigarette smoke and pollen (see, for example, Patent Document 1).

  Furthermore, as another particle detection device, there is one that identifies the diameter of suspended particles based on the continuous output time of an optical particle sensor (see, for example, Patent Document 2).

JP 2001-65969 A JP 2002-195929 A

  However, the first particle detection device requires a plurality of sensors, resulting in an increase in cost.

  Since the second and third particle detection devices use binary output particle sensors, even if the amount of suspended particles in the air changes during the detection time cycle, the detection time of the next cycle The amount of suspended particles after the change cannot be determined until it has elapsed. That is, there is a problem that there is a delay between the change of the amount of suspended particles in the air and the detection of the change.

  In addition, when an analog output particle sensor is used, the sensor itself is expensive, and as with the first particle detection device, the cost increases.

  SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a particle detection apparatus that can quickly determine the amount of suspended particles without causing a detection delay while employing an inexpensive binary output type particle sensor. To do.

As a means for solving the above problems, the present invention provides:
Particle detector
A particle detector that outputs an output corresponding to the amount of received light that changes based on the influence of scattered light from airborne particles in the air when the light emitted from the light emitting element is received by the light receiving element;
A signal determination unit that determines whether the output is high or low by comparing the output from the particle detection unit with a preset threshold;
Storage means for storing the determination result in the signal determination means in units of a predetermined detection time with a time delay;
Arithmetic means for sequentially calculating a high or low output time ratio based on a determination result in each detection time unit stored in the storage means;
Particle amount determination means for determining the amount of suspended particles based on the output time ratio sequentially calculated by the calculation means;
It is set as the structure provided with.

  With this configuration, because of binary output, it is possible to determine the amount of suspended particles every fine time unit, that is, every lapse of the delay time, even though a predetermined detection time is required.

  When the determination result by the signal determination unit is continuously high or low, the failure detection unit further determines that the particle detection unit is in failure by exceeding a preset reference time. It is preferable to provide.

Further, the present invention provides a means for solving the above-described problems,
Particle detector
A particle detector that outputs an output corresponding to the amount of received light that changes based on the influence of scattered light from airborne particles in the air when the light emitted from the light emitting element is received by the light receiving element;
A signal determination means for determining whether the output from the particle detection means is high or low at a predetermined capture interval;
Storage means for storing the determination result in the signal determination means;
Based on the determination result stored in the storage unit, a calculation unit that counts the cumulative number of times that are continuously high or low;
Particle amount determination means for determining the amount of suspended particles based on the cumulative number counted by the calculation means;
It is set as the structure provided with.

  With this configuration, the amount of suspended particles can be easily grasped as a digital amount, and a high calculation processing capability and a large memory are not required. Therefore, an inexpensive configuration can be achieved.

  It is preferable to further include a failure detection means for determining that the particle detection means is in failure when the cumulative number of times calculated by the calculation means exceeds a preset reference number.

Based on the determination result in the signal conversion means, further comprising a particle size determination means capable of determining whether the suspended particles are large particles or small particles,
The calculating means calculates a high or low output time ratio at the detection time when the particle diameter determining means determines that the particle is a small particle, and continuously determines when the particle size is determined to be a large particle. Thus, it is preferable to count the cumulative number of times that become high or low.

  With this configuration, the amount of suspended particles can be accurately grasped based on the difference in particle diameter.

  The arithmetic means preferably divides the detection time by the number of the signal determination means to obtain a delay time, and determines whether the pulse signal output from the signal conversion means is high or low. .

  According to the present invention, the determination result of the signal determination means is stored in the storage means in a predetermined detection time unit with a delay in time, so a predetermined detection time is required for binary output. Despite this, the amount of suspended particles can be determined in fine time units.

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

  FIG. 1 shows a particle detection apparatus according to this embodiment. This particle detection apparatus includes a particle sensor 1 and a microcomputer 2.

  As shown in FIG. 2, the particle sensor 1 includes a light emitting element 3, a light receiving element 4, a signal sorting circuit 5, and an amplifier circuit 6. The light receiving element 4 outputs a voltage value corresponding to the amount of light when the light from the light emitting element 3 is received. That is, if there are floating particles between the two elements, the input at the light receiving element 4 changes due to the scattered light, and this change is output as a voltage value. The signal classification circuit 5 classifies the voltage value output from the light receiving element 4 based on a preset reference voltage value (threshold value). The reference voltage is used to classify the output voltage (1-2 V) from the light receiving element 4 when the suspended particles are small particles (particle diameter: 0.01-1 μm) such as cigarette smoke. The first reference voltage (first threshold) and the output voltage (2.5 V or more) from the light receiving element 4 when the suspended particles are large particles (particle diameter: 7 μm or more) such as pollen or dust. A second reference voltage (second threshold) for classification is set. Here, a value (for example, 1 V) that can distinguish the output voltage (1 to 2 V) from the light receiving element 4 is used as the first reference voltage, and the output voltage (2.5 V from the light receiving element 4 is used as the second reference voltage. A value (for example, 2.5 V) that can be distinguished is used.

  An output signal from the particle sensor 1 is input to the particle size separation circuit 7. The particle size separation circuit 7 includes a first comparator 8A and a second comparator 8B. The first reference voltage obtained by dividing the power supply voltage V by the resistors R1 and R2 is input to the positive input terminal of the first comparator 8A. A second reference voltage obtained by dividing the power supply voltage V by the resistors R3 and R4 is input to the positive input terminal of the second comparator 8B. The sensitivity can be adjusted by allowing the power supply voltage VDD to be applied from the input port to the positive input terminal of the second comparator 8B.

  The output signals from the particle sensor 1 are input to the negative input terminals of both the comparators 8A and 8B. Further, noise removing capacitors C1 and C2 and pull-up resistors R5 and R6 are connected to the output terminal side lines of the comparators 8A and 8B, respectively.

  The first comparator 8A outputs a Low signal only when the output voltage exceeds the first reference voltage by comparing the output voltage applied from the particle sensor 1 with the first reference voltage. In other cases, a High signal is output (so-called binary output). As a result, the Low signal is output from the output terminal of the first comparator 8A not only when the particle diameter of the suspended particles is large but also when the particle diameter of tobacco smoke or the like is small. The output signal from the first comparator 8A is input to the microcomputer 2 via the first output port P1.

  Further, in the second comparator 8B, the output voltage applied from the particle sensor 1 is compared with a second reference voltage larger than the first reference voltage, so that the output voltage is the same as in the case of the first comparator 8A. A low signal is output only when the voltage exceeds the second reference voltage, and a high signal is output otherwise (so-called binary output). As a result, a Low signal is output from the output terminal from the second comparator 8B only when the particle size of the suspended particles is large. The output signal from the second comparator 8B is input to the microcomputer 2 via the second output port P2.

  As shown in FIG. 1, the microcomputer 2 includes a storage unit 9, a control unit 10 (CPU), an input / output unit 11, and the like, and turns on / off a power transistor Tr that supplies power to the particle sensor 1.

  The storage unit 9 includes a ROM 12 (Read Only Memory) and a RAM 13 (Random Access Memory).

  The ROM 12 stores a control program. Based on the output signal from the particle sensor 1, the control program executes a predetermined calculation process as will be described later.

In the RAM 13, a detection signal from the particle sensor 1 is stored in a part of the storage area. Here, with 2 bytes (= 2 ¹⁶ = 65536) as one unit, 16 areas are used for storing detection signals from the particle sensor 1. Fifteen regions (first to fifteen regions) are used for storing signals output from the first output port P1, and the remaining one region (sixteenth region) is a signal output from the second output port P2. Used for memory. Specifically, in each cell of each region, “0” is stored in every 1 msec when a High signal is input, and “1” is stored when a Low signal is input. The data stored in each cell in the first to fifteenth areas is rewritten to the next data when a predetermined detection time (30 sec) has elapsed since the start of storage.

  The control unit 10 executes a control program stored in the ROM 12. That is, based on the output signal from the first output port P1 of the particle size separation circuit 7, first, data (“1” or “0”) is sequentially stored in each cell of the first region. Then, when a preset delay time elapses, data is similarly stored in each cell of the second area. Similarly, data is stored up to the fifteenth area. The delay time is a time obtained by dividing the detection time by the number of areas for storing. Here, since the detection time is 30 sec, 2 sec divided by the number of areas 15 is the delay time. The delay time can be shortened by shortening the detection time or increasing the number of areas to be stored. That is, sensitivity can be increased by shortening the delay time. In each region, the output signal from the particle sensor 1 is stored at a constant period (detection time), the result is counted, and the data is cleared. Further, based on the output signal from the second output port P2 of the particle size separation circuit 7, data is sequentially stored in each cell of the sixteenth region, and the result is counted.

  Next, the operation of the particle detection apparatus having the above configuration will be described.

(Dust detection processing-small particles)
In the small particle dust detection process, first, an output signal from the first output port P1 based on a detection signal from the particle sensor 1 is read at a predetermined capture interval Ti (1 msec). The output signal from the first output port P1 input to the microcomputer 2 is a case where the suspended particles are small particles (including a case where large particles are mixed). For example, as shown in FIGS. Waveform. That is, the waveform of the output signal includes a Low signal having a pulse width of about 10 msec to 90 msec. If there are many particles floating in the air, the waveform intermittently includes a large number of Low signals.

  Then, based on the read input signal from the first output port P1, as shown in FIG. 4, the data corresponding to each cell in the first area (“1” if the Low signal, “High” signal) "0") is stored. When the delay time Td (here 2 sec) elapses, as shown in FIG. 6, the storage of data in each cell of the second area is started in parallel with the storage in the first area. To the 15th area. In this way, in each area, data corresponding to the input signal is sequentially stored while shifting the time.

  Subsequently, if data is stored in the first area for the detection time Tm (30 sec), “1” is counted among the stored data. Then, the data of the first area where the counting is completed is cleared and prepared for the next input data. Note that the storage of data in the first area is resumed when the delay time Td has elapsed since the start of storage in the fifteenth area.

  Thereafter, based on the obtained count value, the suspended particle amount, that is, the dirt level is determined according to the determination table shown in FIG. When the count value Cn is less than 1000 msec, the dirt (floating particle) level is “0”, and when the count value is 1000 msec or more and less than 2000 msec, the dirt level is “1” and the count value is 2000 msec or more and less than 3000 msec. In this case, the contamination level is “2”, and when the count value is 3000 msec or more, it is determined that the contamination level is “3”. The three threshold values (1000 msec, 2000 msec, and 3000 msec) of the count value Cn are values at which the ratio of the output time to the detection time Tm (30 sec) is 1/30, 1/15, and 1/10, respectively.

  Hereinafter, in the same manner as in the first area, every time the detection time Tm elapses in the second to fifteen areas, “1” is counted based on the data stored in each cell in each area. The contamination level is determined according to the determination table shown in FIG. As described above, in the first to fifteenth areas, the stain level can be determined every time the delay time Td elapses. Therefore, until the detection time Tm elapses as in the prior art, the determination of the next stain level is made to wait. There is no need. That is, it becomes possible to quickly detect a change in the dirt level. In addition, since the dirt level is determined in units of a predetermined detection time Tm, even if large particles such as pollen and dust are mixed in the floating particles in the initial stage, the large particles remain in the same place for a long time. Since it is not a stagnation, its influence can be eliminated.

  As described above, the particle detection sensor capable of determining the level of air contamination by small particles is employed in, for example, an air cleaner. In the air cleaner, the operating strength is adjusted based on the determination result. That is, the operating intensity is set according to the dirt level, and the operating intensity is selected according to the determination table shown in FIG. 7 according to the determined dirt level. If the level is “0”, the air-cleaning is not started while maintaining the stopped state. Moreover, if it is level "1," it will stop after driving for 2 minutes with weak wind. If the level is “2”, the vehicle is operated for 3 minutes with medium wind, and is operated for 2 minutes with light wind, and then stops. Further, if the level is “3”, the vehicle is driven for 3 minutes with strong wind, is driven for 3 minutes with medium wind, is driven for 2 minutes with low wind, and then stops. At this time, the operation intensity determined last time may be compared with the operation intensity selected this time, and air cleaning may be executed with the higher operation intensity. When the driving intensity is the same between the previous time and the current time, the time measurement at each driving intensity may be newly performed from this time. For example, in an operation based on level “2”, after driving for 30 seconds with medium wind, if it is determined as level “2”, the operation with medium wind may be counted again from the beginning.

(Dust detection processing-large particles)
In the large particle dust detection process, first, an output signal (High signal or Low signal) from the second output port P2 of the particle size separation circuit 7 is read. The output signal from the second output port P2 to the microcomputer 2 has, for example, a waveform as shown in FIG. That is, when large particles such as pollen are floating in the air, the output signal from the second output port P2 outputs a Low signal for a relatively long time.

  Therefore, based on the output signal from the second output port P2, data corresponding to each cell in the sixteenth area (“1” for the Low signal and “0” for the High signal) are sequentially taken in a predetermined order. The data is stored at every insertion interval Td (1 msec).

  When the data stored in each cell changes from “0” corresponding to the High signal to “1” corresponding to the Low signal, the count starts, and when the data changes from “1” to “0”, Stop counting. Subsequently, the pulse width is calculated based on the count number. However, the next count is not started until a predetermined waiting time (for example, 1 sec) elapses after the count is stopped.

  Thereafter, the pollen level is determined according to the determination table shown in FIG. 8 based on the calculated pulse width. That is, if the pulse width is less than 80 msec, it is level “0”, if it is 80 msec or more and less than 100 msec, it is level “1”, and if it is 100 msec or more and less than 310 msec, it is level “2”. judge. However, when the pulse width W calculated based on the count value exceeds an upper limit value (for example, 310 msec), the pollen level is not determined. In the large particle dust detection process, the output signal from the second output port P2 includes the influence of small particles, but in the case of small particles, a high or low signal is not continuously output. Since it becomes intermittent, it is possible to detect large particles appropriately by detecting the pulse width W.

  The particle detection sensor capable of determining the level of air contamination by large particles as described above is employed in, for example, an air cleaner. In the air cleaner, the operation intensity is adjusted based on the determination result. That is, if the level is “0”, the stop state is maintained. If the level is “1”, the air is blown for 2 minutes with the medium wind and then blown for 3 minutes with the weak wind. Blow for 1 minute with strong wind, blow for 2 minutes with medium wind, blow for 3 minutes with weak wind, and then stop. At this time, similarly to the small particle dust detection process, the previously determined operating intensity may be compared with the currently selected operating intensity, and air cleaning may be executed with the higher operating intensity. When the driving intensity is the same between the previous time and the current time, the time measurement at each driving intensity may be newly performed from the current time.

(Disconnection detection processing)
In the disconnection detection process, the particle sensor 1 continues to output a Low signal from the particle diameter determination circuit due to disconnection of the circuit or the like in both cases of small particles and large particles. Based on “1”, it is determined that there is a failure from the accumulated time (or accumulated number of times).

  When a failure is determined based on an output signal from the first output port P1 (small particles), data stored in each cell in the first to 15th areas of the RAM 13 is input from the first output port P1 of the particle size discrimination circuit. The number for each detection time Tm that becomes “1” by the Low signal is counted. Then, it is determined whether or not the obtained count value (cumulative time) exceeds a preset reference time (time that is a criterion for failure determination). Usually, in the case of small particles such as cigarette smoke, the accumulated time per detection time Tm (30 sec) is about 5 sec at the maximum. Therefore, here, the accumulation time is set to 20 seconds, and it is determined whether the result is a result of detecting small particles or a failure. The reference time was calculated by conducting a deodorization performance test based on JEM1467, which is a performance measurement standard for household air purifiers established by the Japan Electrical Manufacturers' Association, and multiplying the cumulative time counted as a result by a safety factor. .

  When a failure is determined based on an output signal from the second output port P2 (large particle), data stored in each cell in the sixteenth area of the RAM 13 is input from the second output port P2 of the particle size discrimination circuit. The number which becomes “1” continuously by the Low signal is counted. Then, it is determined whether or not the obtained count value (cumulative number, here, pulse width) exceeds a preset reference number (here, reference pulse width). Usually, in the case of large particles such as pollen and dust, the detected maximum pulse width is about 300 msec, so the reference pulse width is 310 msec. Further, once the detected pulse width exceeds the reference pulse width, after waiting for 1 sec, the pulse width is specified based on the count value again in the same manner as described above, and compared with the reference pulse width. Thereby, if the pulse width detected continuously 16 times exceeds the reference pulse width, it is determined that there is a failure. The reason why the number of determinations is 16 is to match the failure determination time with small particles (20 sec) (16 times: (310 msec + 1000 msec) × 16 = 20960 msec).

  As a result of performing the disconnection detection process as described above, if it is determined that the particle sensor 1 is disconnected, an LED (not shown) may be turned on or a buzzer (not shown) may be sounded to notify the user. .

  In the above-described embodiment, the particle sensor 1 is configured to detect both the case where the suspended particles are small particles and the case where the suspended particles are large particles. However, the particle sensor 1 may be configured to detect only one of them. is there.

  Further, the output from the first output port P1 includes the detection result of the large particles. However, the output component from the second output port P2 may be removed to obtain only the detection result of the small particles. Is possible. According to this, it becomes possible to further improve detection accuracy.

  Further, the output signal from the first output port P1 of the particle sensor 1 is stored as digital data in the RAM 13, but may be stored as time data by using an analog timer. This makes it possible to make a more accurate determination.

  Further, when the rise of the particle sensor 1 is unstable, data is stored in the RAM 13 after a certain time has elapsed since the power transistor Tr was turned on, or for a certain time after the power transistor Tr was turned on. It is preferable not to reflect the count Cn including the data of the output P1 in the operation.

It is a circuit diagram of the particle | grain detection apparatus which concerns on this embodiment. It is a circuit diagram of the particle sensor shown in FIG. It is a wave form diagram of the output signal each inputted into the microcomputer from the 1st output port of the particle sensor of Drawing 1, and the 2nd output port. It is a wave form diagram of the output signal inputted into the microcomputer from the 1st output port of the particle sensor of Drawing 1. It is a wave form diagram of the output signal inputted into the microcomputer from the 2nd output port of the particle sensor of Drawing 1. It is a timing chart figure which shows the timing memorize | stored in RAM of a microcomputer based on the output signal input into the microcomputer from the 1st output port of the particle | grain sensor of FIG. 3 is a contamination level determination table determined by the CPU of the microcomputer of FIG. 1. It is a pollen level determination table determined by the CPU of the microcomputer of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Particle sensor 2 ... Microcomputer 3 ... Light emitting element 4 ... Light receiving element 5 ... Signal classification circuit 6 ... Amplifier circuit 7 ... Particle diameter classification circuit 8A ... 1st comparator 8B ... 2nd comparator 9 ... Memory | storage part 10 ... Control part 11 ... Input / output unit 12 ROM
13 ... RAM
Ti ... Capture interval Td ... Delay time Tm ... Detection time

Claims (9)

A particle detector that outputs an output corresponding to the amount of received light that changes based on the influence of scattered light from airborne particles in the air when the light emitted from the light emitting element is received by the light receiving element;
A signal determination unit that determines whether the output is high or low by comparing the output from the particle detection unit with a preset threshold;
Storage means for storing the determination result in the signal determination means in units of a predetermined detection time with a time delay;
Arithmetic means for sequentially calculating a high or low output time ratio based on a determination result in each detection time unit stored in the storage means;
Particle amount determination means for determining the amount of suspended particles based on the output time ratio sequentially calculated by the calculation means;
A particle detection apparatus comprising:   When the determination result by the signal determination unit is continuously high or low, the failure detection unit further determines that the particle detection unit is in failure by exceeding a preset reference time. The particle detection apparatus according to claim 1, further comprising: A particle detector that outputs an output corresponding to the amount of received light that changes based on the influence of scattered light from airborne particles in the air when the light emitted from the light emitting element is received by the light receiving element;
A signal determination means for determining whether the output from the particle detection means is high or low at a predetermined capture interval;
Storage means for storing the determination result in the signal determination means;
Based on the determination result stored in the storage unit, a calculation unit that counts the cumulative number of times that are continuously high or low;
Particle amount determination means for determining the amount of suspended particles based on the cumulative number counted by the calculation means;
A particle detection apparatus comprising:   The particle according to claim 3, further comprising a failure detection unit that determines that the particle detection unit is in failure when the cumulative number of times calculated by the calculation unit exceeds a preset reference number. Detection device. Based on the determination result in the signal conversion means, further comprising a particle size determination means capable of determining whether the suspended particles are large particles or small particles,
The calculating means calculates a high or low output time ratio at the detection time when the particle diameter determining means determines that the particle is a small particle, and continuously determines when the particle size is determined to be a large particle. The particle detection device according to claim 1, wherein the cumulative number of times of high or low is counted.   The calculation means divides the detection time by the number of the signal determination means to obtain a delay time, and determines whether the pulse signal output from the signal conversion means is high or low. The particle detector according to any one of claims 1 to 5. When light received from the light emitting element is received by the light receiving element, the output corresponding to the amount of received light that changes based on the influence of scattered light from airborne particles in the optical path is compared with a preset threshold value. To determine whether it is high or low,
The determination results are each stored in predetermined detection time units with a time delay,
Based on the determination result in each detection time unit, the output time ratio of high or low is sequentially calculated,
A particle detection method, comprising: determining an amount of suspended particles based on a sequentially calculated output time ratio. When light received from the light emitting element is received by the light receiving element, the output corresponding to the amount of received light that changes based on the influence of scattered light from airborne particles in the optical path is compared with a preset threshold value. To determine whether it is high or low,
Memorize the judgment result,
Based on the stored determination result, the number of high or low continuous outputs in the detection time is calculated,
A particle detection method, comprising: determining an amount of suspended particles based on the calculated number of continuous outputs. Based on the determination result, determine whether the suspended particles are large particles or small particles,
If it is determined to be a small particle, the output time ratio of high or low at the detection time is calculated, and if it is determined to be a large particle, the number of continuous high or low output times at the detection time. The particle detection method according to claim 7 or 8, wherein

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