JP2014017218A - Ion generation device, and abnormal discharge detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion generation device capable of appropriately detecting abnormal discharge generated between a discharge electrode and a foreign matter with a high reliability.SOLUTION: An ion generation device comprises: a detection electrode 4 arranged so as to be opposed to a discharge electrode 2; an impedance circuit 6 connected between the detection electrode 4 and a grounded part 5; and abnormal discharge detection means 7 for detecting presence or absence of generation of abnormal discharge on the basis of a voltage signal Vp outputted from the impedance circuit 6. When the abnormal discharge is generated, the abnormal discharge detection means 7 acquires a high-frequency component including a frequency component composing a pulse signal, included in the voltage signal Vp by means of filtering means 11, and detects presence or absence of the pulse signal that is caused by the generation of abnormal discharge from the high-frequency component by means of pulse signal detection means 12.

Description

  The present invention relates to a corona discharge type ion generator.

  2. Description of the Related Art Conventionally, a corona discharge type ion generating apparatus that generates positive and negative air ions by corona discharge has been conventionally used as, for example, a static eliminating apparatus for performing static elimination on an object to be eliminated.

  In this type of ion generating apparatus, as can be seen in, for example, Patent Document 1, an apparatus that can detect that an electrode has a defective discharge or an abnormal discharge state is known. .

  In Patent Document 1, a ground electrode (so-called counter electrode) opposite to a discharge electrode is connected to a ground portion through a circuit having a resistance element, a light emitting diode, a photocoupler light emitting element, etc. A technique for detecting the occurrence of abnormal discharge or the occurrence of defective discharge based on the light emission state or the output of a light receiving element of a photocoupler is described.

Japanese Patent No. 2816667

  By the way, as an abnormal discharge phenomenon that can occur in the ion generating device, when a foreign object that is grounded (or connected to the grounding part) approaches or contacts the discharge electrode of the ion generating device, the discharge electrode and the foreign material There is a discharge phenomenon that occurs between objects.

  Hereinafter, unless otherwise specified, in this specification, “abnormal discharge” means discharge generated between the discharge electrode and the foreign object as described above. Further, the foreign object means an object that is not a component (such as a counter electrode) provided in the ion generation device in order to generate a normal corona discharge.

  Since abnormal discharge as described above tends to be spark discharge, it tends to cause problems such as damage to the discharge electrode or rapid deterioration, or damage to a high voltage generating circuit that applies a high voltage to the discharge electrode.

  Therefore, it is desired that when an abnormal discharge as described above occurs, it can be detected promptly.

  However, in the conventional ion generator as shown in Patent Document 1, it has been difficult to reliably detect abnormal discharge generated between the discharge electrode and the foreign object for the following reason.

  That is, when an abnormal discharge occurs between the discharge electrode and the foreign object, the discharge current itself flows between the discharge electrode and the foreign object. The current does not flow through the light emitting diodes in the circuit between them or the light emitting element of the photocoupler.

  Further, according to various experiments and examinations by the inventors of the present application, the abnormal discharge between the ground electrode and the ground portion due to a voltage induced in the ground electrode due to an electromagnetic wave phenomenon (specifically, a displacement current in space). Although current fluctuations according to the occurrence of can occur, the current fluctuations are normally pulse-like fluctuations with a relatively short time width. For this reason, it is extremely difficult to detect the current fluctuation based on the light emission output of the light emitting diode or the light emitting element of the photocoupler.

  For this reason, it has been difficult for the conventional ion generating apparatus as disclosed in Patent Document 1 to reliably detect abnormal discharge generated between the discharge electrode and the foreign object.

  The present invention has been made in view of such a background, and provides an ion generation apparatus and an abnormal discharge detection method capable of appropriately detecting an abnormal discharge generated between a discharge electrode and a foreign object with high reliability. The purpose is to provide.

In order to achieve the above object, the ion generating apparatus of the present invention generates a corona discharge from the discharge electrode by applying a positive or negative high voltage to the discharge electrode, and generates air ions by the corona discharge. In the ion generator,
A detection electrode disposed opposite to the discharge electrode, connected between the detection electrode and the grounding portion, and outputs a voltage signal corresponding to a current flowing between the detection electrode and the grounding portion. An abnormal discharge that detects whether or not an abnormal discharge, which is a discharge that occurs between the discharge electrode and a foreign object other than the detection electrode, is input based on the voltage signal and the impedance circuit. Detecting means, and when the abnormal discharge occurs, the abnormal discharge detecting means allows a high frequency component including a frequency component that composes a pulse signal included in the voltage signal due to the occurrence of the abnormal discharge to pass therethrough. Filtering means for applying a filtering process to the voltage signal having a frequency pass characteristic for cutting off a low frequency component having a frequency lower than that of the high frequency component, and an output of the filtering means Pulse signal detecting means for executing processing for detecting a signal corresponding to the pulse signal, and the occurrence of the abnormal discharge depending on whether the signal corresponding to the pulse signal is detected by the pulse signal detecting means. It is configured to detect presence or absence (first invention).

  The impedance circuit means a circuit composed of one or more circuit elements having impedance, such as a resistance element and a capacitance element.

  Further, the positive or negative high voltage applied to the discharge electrode may be a DC voltage having only one of positive and negative polarities, or may be an AC voltage whose polarity changes alternately. .

  More specifically, the foreign object means an object that is not a constituent element provided in the ion generating apparatus in order to generate a normal corona discharge as described above.

  The same applies to other inventions described later.

  According to the first aspect of the present invention, when the abnormal discharge occurs in a state where a positive or negative high voltage is applied to the discharge electrode, the magnitude of the potential of the discharge electrode (potential with respect to the ground portion) is usually small. , Get smaller rapidly.

  On the other hand, when the voltage applied to the discharge electrode changes, a displacement current corresponding to the capacitance of the space between the discharge electrode and the detection electrode is generated. A voltage is induced in the detection electrode. The induced voltage causes a current corresponding to the displacement current (current having the same current value as the displacement current) to flow between the discharge electrode and the detection electrode through the impedance circuit.

  In particular, when the abnormal discharge occurs, the magnitude of the potential of the discharge electrode (potential with respect to the grounding portion) rapidly decreases, and therefore, between the discharge electrode and the detection electrode, A pulse-like displacement current with a small time width is generated. A pulsed current corresponding to this displacement current flows through the impedance circuit.

  As a result, the voltage signal output from the impedance circuit includes a pulse signal corresponding to the pulse-like displacement current. Such a pulse signal is composed of relatively high frequency components.

  Therefore, in the first invention, the filtering process is performed on the voltage signal output from the impedance circuit by the filtering means. In this filtering process, when the abnormal discharge occurs, a high frequency component including a frequency component composing a pulse signal included in the voltage signal due to the occurrence of the abnormal discharge is passed, and more than the high frequency component. Cuts off low frequency components at low frequencies.

  For this reason, when the voltage signal includes the pulse signal resulting from the occurrence of the abnormal discharge, a signal that significantly includes a signal corresponding to the pulse signal (pulse-shaped signal). Obtained as an output of the filtering means.

  Furthermore, in the first invention, the pulse signal detection means executes processing for detecting a signal corresponding to the pulse signal from the output of the filtering means. At this time, if the voltage signal includes the pulse signal resulting from the occurrence of the abnormal discharge, the output of the filtering means is a signal corresponding to the pulse signal (pulse-like) as described above. Signal) is significantly included.

  Accordingly, when the voltage signal includes the pulse signal resulting from the occurrence of the abnormal discharge, the pulse signal can be appropriately detected.

  Then, the abnormal discharge detection means detects whether or not the abnormal discharge has occurred depending on whether or not the pulse signal is detected by the pulse signal detection means. That is, the abnormal discharge detection means detects that the abnormal discharge has occurred when the pulse signal is detected by the pulse signal detection means.

  Thereby, according to 1st invention, when abnormal discharge generate | occur | produces between a discharge electrode and a foreign material object, generation | occurrence | production of the abnormal discharge can be detected appropriately with high reliability.

  In the first invention, the pulse signal detection means has a pulse shape having a voltage value greater than a predetermined value set in advance and a time width greater than a predetermined width set from the output of the filtering means. It is preferable that the signal is detected as a signal corresponding to the pulse signal (second invention).

  Here, the output of the filtering means generally includes a high-frequency noise component. However, the pulse signal that is included in the voltage signal due to the occurrence of the abnormal discharge is usually larger in magnitude (peak value) than a general noise component, and the time width is generally Larger than typical noise components.

  Accordingly, in the second invention, the pulse signal detecting means has a pulse having a voltage value greater than a predetermined value set in advance and a time width greater than a predetermined width set from the output of the filtering means. Is detected as a signal corresponding to the pulse signal.

  As a result, the pulse signal detection means has a high signal (pulse-like signal) corresponding to the pulse signal that is included in the voltage signal due to the occurrence of the abnormal discharge from the output of the filtering means. It can be detected appropriately with reliability.

  The predetermined value related to the magnitude of the pulse signal and the predetermined width related to the time width are based on experiments or the like in advance so that a signal corresponding to the pulse signal can be distinguished from a noise component signal. Set it up.

  The ion generator according to the first or second aspect of the present invention, as one form of the ion generator, generates a corona discharge from the discharge electrode by, for example, applying a positive or negative high voltage to the discharge electrode at a constant period. The ion generator to be used may be used. In this case, the filtering means is preferably configured so that the high-frequency component to be passed is a component having a frequency higher than at least the frequency corresponding to the certain period (third invention). .

  Here, in the ion generator that applies a positive or negative high voltage to the discharge electrode at a constant cycle, the abnormal discharge does not occur, even when the corona discharge is generated normally, The voltage signal includes a frequency component having a frequency corresponding to the certain period (period in which a positive or negative high voltage is applied to the discharge electrode), that is, a frequency that is an inverse value of the one point period. become.

  In this case, the filtering means in the third invention is configured so that the high-frequency component to be passed is at least a frequency component higher than the frequency corresponding to the certain period. Does not always include a frequency component having a frequency corresponding to the certain period.

  Therefore, a pulse-like signal corresponding to the pulse signal resulting from the occurrence of the abnormal discharge is obtained as a highly significant signal at the output of the filtering means when the abnormal discharge occurs.

  Therefore, according to the third aspect, when the pulse signal resulting from the occurrence of the abnormal discharge is included in the voltage signal, a pulse signal corresponding to the pulse signal is output from the output of the filter means. Thus, the detection can be appropriately performed with higher reliability.

  The ion generator of the third invention may be an ion generator that alternately applies positive and negative high voltages to the discharge electrodes. The positive and negative high voltages applied to the discharge electrodes are not limited to sinusoidal voltages but may be pulsed voltages.

  In the first to third aspects of the invention, it is preferable that the abnormal discharge detection means is configured to cut off the application of the high voltage to the discharge electrode when detecting that the abnormal discharge has occurred. (4th invention).

  According to the fourth aspect of the invention, when the abnormal discharge occurs, the application of the high voltage to the discharge electrode is interrupted. For this reason, it is possible to prevent the discharge electrode from being damaged or rapidly deteriorated, or the high voltage generating circuit generating the high voltage from being damaged.

  In the first to fourth inventions, the ion generating device may include a plurality of discharge electrodes. In this case, the discharge electrode and the impedance circuit may be provided for each discharge electrode.

  However, in the case of having a plurality of the discharge electrodes, at least one of the plurality of discharge electrodes facing the N (N: integer of 2 or more) discharge electrodes of the group is used. One or more detection electrodes opposed to the N discharge electrodes may be connected to a single impedance circuit so as to have electrodes (fifth invention).

  According to the fifth invention, since a single impedance circuit can be shared for N discharge electrodes, it is possible to simplify the configuration of the ion generation device capable of detecting the occurrence of the abnormal discharge, and the ion generation device. The cost can be reduced.

  In the fifth aspect of the invention, the detection electrodes facing the N discharge electrodes may be a plurality of detection electrodes respectively facing the N discharge electrodes. It may be a detection electrode having an integral structure common to the discharge electrode.

  In the first to fifth aspects of the present invention, in addition to the detection electrode, a counter electrode disposed in the vicinity of the discharge electrode may be provided to face the discharge electrode in order to generate a corona discharge. Good.

  However, the detection electrode may be arranged so as to function as a counter electrode that generates corona discharge between the opposing discharge electrodes (sixth invention).

  According to the sixth aspect of the invention, the number of parts of the ion generating device can be reduced because the detection electrode also functions as the counter electrode. Therefore, it is possible to simplify the configuration of the ion generation device that can detect the occurrence of abnormal discharge, and to reduce the cost of the ion generation device.

  Next, the method for detecting an abnormal discharge of the ion generator of the present invention is a method for generating a corona discharge from the discharge electrode by applying a positive or negative high voltage to the discharge electrode, and generating air ions by the corona discharge. In the generating device, a method for detecting the presence or absence of occurrence of abnormal discharge, which is a discharge generated between the discharge electrode and a foreign object other than the detection electrode disposed opposite to the discharge electrode, the detection An impedance circuit connected between the detection electrode and the grounding section and outputting a voltage signal corresponding to the current flowing between the detection electrode and the grounding section, and when the abnormal discharge occurs, Frequency-passing characteristic that allows high-frequency components including frequency components that compose the pulse signal included in the voltage signal to pass due to occurrence and blocks low-frequency components having a frequency lower than the high-frequency components A step of performing filtering processing on the voltage signal, and processing for detecting a signal corresponding to the pulse signal from the signal obtained by the filtering processing, and whether a signal corresponding to the pulse signal is detected. And detecting the presence or absence of occurrence of the abnormal discharge.

  According to the seventh aspect of the invention, when the abnormal discharge occurs by applying the filtering process to the voltage signal output from the impedance circuit, the abnormal discharge occurs as in the first aspect. A signal that significantly includes a signal (pulse-like signal) corresponding to the pulse signal resulting from the above is obtained.

  Accordingly, the pulse signal resulting from the occurrence of the abnormal discharge can be appropriately detected from the signal obtained by the filtering process.

  Therefore, whether or not the abnormal discharge has occurred can be detected based on whether or not the pulse signal is detected.

  Therefore, according to the seventh aspect, when an abnormal discharge occurs between the discharge electrode and the foreign object, the occurrence of the abnormal discharge can be appropriately detected with high reliability.

  In the seventh invention, the same aspects as those in the second to sixth inventions can be adopted.

  Supplementally, in the present invention described above, a blowing unit such as a fan that blows air ions generated by the corona discharge toward the static elimination object may be provided.

The figure which shows schematic structure of the ion generator of one Embodiment of this invention. FIG. 2A is a view showing an example of the arrangement configuration of the discharge electrode and the detection electrode, and FIG. 2B is a view taken in the direction of arrow II in FIG. The figure which shows the specific structure of the impedance circuit and abnormal discharge detection output generation circuit which are shown in FIG. The figure which shows the example of the circuit structure of the high pass filter and pulse signal detection part which are shown in FIG. The graph which shows the example of the change of the electric potential which generate | occur | produces in the discharge electrode of the ion generator of embodiment. 6A to 6F are graphs for explaining the operation of the abnormal discharge detection output generation circuit of the embodiment. The figure for demonstrating the deformation | transformation aspect of embodiment of this invention.

  An embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the ion generator 1 of the present embodiment is configured to generate positive and negative air ions by corona discharge, and a discharge electrode 2 and positive and negative applied to the discharge electrode 2. And a high voltage generation circuit 3 for generating a high voltage.

  Furthermore, the ion generator 1 is connected between the detection electrode 4 disposed opposite to the discharge electrode 2 and the detection electrode 4 and the grounding part 5 as a configuration for detecting whether or not abnormal discharge has occurred. And the abnormal discharge detection output generation circuit 7 to which the voltage signal Vp output from the impedance circuit 6 is input.

  The abnormal discharge is a discharge between the discharge electrode 2 and a foreign object other than the detection electrode 4.

  The high voltage generation circuit 3 is a circuit that alternately outputs a pulsed positive high voltage and a negative high voltage from the output terminal 3a at a constant cycle. In the present embodiment, the frequency of the high voltage output from the high voltage generation circuit 3 (the frequency of the reciprocal value of the positive and negative high voltage generation cycles) is, for example, 260 Hz.

  As such a high voltage generation circuit 3, for example, a circuit proposed by the applicant of the present application in Japanese Patent Application Laid-Open No. 2009-4177 is adopted. However, the high voltage generation circuit 3 may have another known circuit configuration. Further, the high voltage generation circuit 3 may be a circuit that outputs a sinusoidal AC high voltage.

  The discharge electrode 2 is composed of a needle-like conductor so as to have a sharp tip. In the present embodiment, the discharge electrode 2 is connected to the output terminal 3 a of the high voltage generation circuit 3 via a capacitive member 8 made of an insulator and a high voltage cable 9. The capacitive member 8 is a member that functions as a capacitor having a predetermined capacitance value. Therefore, the discharge electrode 2 is connected to the output terminal 3a of the high voltage generation circuit 3 in the form of capacitive coupling.

  A resistance element may be interposed in series with the capacitive member 8 between the discharge electrode 2 and the output terminal 3 a of the high voltage generation circuit 3. Alternatively, instead of the capacitive member 8, the discharge electrode 2 is connected to the high voltage generation circuit 3 via a resistance element (that is, the discharge electrode 2 is connected to the output terminal 3 a of the high voltage generation circuit 3 in the form of resistance coupling. Connection).

  The detection electrode 4 is made of a conductor and is disposed so as to face the discharge electrode 2 in the vicinity. More specifically, in this embodiment, as shown in FIGS. 2A and 2B, the detection electrode 4 is formed in an annular shape, for example. The detection electrode 4 surrounds the periphery of the tip of the discharge electrode 2 (in other words, in a direction perpendicular to the axial direction of the discharge electrode 2 so as to be spaced from the outer peripheral surface of the discharge electrode 2). ), Which is arranged coaxially with the discharge electrode 2.

  However, for example, as shown by a two-dot chain line in FIG. 2 (a), the detection electrode 4 has a slight distance from the tip of the discharge electrode 2 in the axial direction of the discharge electrode 2. It may be arranged on the front side. Further, the shape of the detection electrode 4 is not limited to an annular shape, and may be a linear shape or a plate shape.

  Supplementally, the ion generating apparatus 1 of the present embodiment is used as a static eliminator for neutralizing a static elimination object (not shown). For this reason, in the ion generator 1 of this embodiment, when performing static elimination of the static elimination target object, positive and negative air ions generated by corona discharge in the vicinity of the discharge electrode 2 are transferred to the front of the discharge electrode 2. 2, it is moved toward the front side of the discharge electrode 2 by an air supply mechanism (blower unit) such as a blower fan (not shown) as indicated by a broken arrow in FIG. Thus, air supply (air blowing) is performed.

  The detection electrode 4 discharges in the direction perpendicular to the axial direction of the discharge electrode 2 as described above in order to prevent the transfer of air ions from the discharge electrode 2 side to the static elimination object as much as possible. The electrode 2 is disposed so as to be spaced from the electrode 2.

  In the present embodiment, the detection electrode 4 also functions as a counter electrode that generates corona discharge with the discharge electrode 2. The distance between the detection electrode 4 and the tip of the discharge electrode 2 (or the radius of the detection electrode 4) can appropriately generate corona discharge between the discharge electrode 2 and the detection electrode 4. Is set to

  Here, according to the experiments and examinations of the inventors of the present application regarding the arrangement of the detection electrode 4, in order to appropriately detect whether or not the abnormal discharge has occurred, the tips of the detection electrode 4 and the discharge electrode 2 are detected. The distance in the axial center direction of the discharge electrode 2 is a distance within the range of −50 to 50 mm (preferably, a distance within the range of −50 to 0 mm), and the distance between the detection electrode 4 and Discharge so that the distance between the tips of the discharge electrodes 2 in a direction perpendicular to the axial center direction of the discharge electrodes 2 is a distance of 50 mm or less (preferably, a distance within a range of 10 to 30 mm). It is desirable to set the arrangement position of the detection electrode 4 with respect to the electrode 2.

  Note that the distance in the axial direction of the discharge electrode 2 is more specifically the distance from the tip of the discharge electrode 2 to the base end side of the discharge electrode 2 as a negative distance (−50 mm or the like), and the tip of the discharge electrode 2. A distance away from the base end side of the discharge electrode 2 to the side opposite to the base end side is defined as a positive distance (50 mm or the like). For example, the distance in the axial direction of the discharge electrode 2 between the detection electrode 4 and the tip of the discharge electrode 2 indicated by a solid line in FIG. 2A is a negative distance, and the difference between the two points in FIG. The distance in the axial direction of the discharge electrode 2 between the detection electrode 4 indicated by a line and the tip of the discharge electrode 2 is a positive distance.

  Supplementally, the space between the discharge electrode 2 and the detection electrode 4 is electrically expressed by an equivalent circuit as indicated by reference numeral A in FIG. This equivalent circuit A has a resistance of a discharge current that flows through a corona discharge between the discharge electrode 2 and the detection electrode 4 to the capacitive element Ca corresponding to the capacitance between the discharge electrode 2 and the detection electrode 4. This is a circuit in which corresponding resistance elements Rdis are connected in parallel via a switch SWdis.

  In this case, the switch SWdis is a switch that is turned on when a corona discharge is generated and is turned off when a corona discharge is not generated. Therefore, the equivalent circuit A is configured by a parallel circuit of the capacitive element Ca and the resistance element Rdis in the state where the corona discharge is generated, and is configured by the capacitive element Ca when the corona discharge is not generated.

  The impedance circuit 6 is a circuit configured by circuit elements having impedance. In this embodiment, the impedance circuit 6 is a circuit configured by a single resistance element 10 as shown in FIG.

  The impedance circuit 6 outputs a voltage generated in the resistance element 10 as a voltage signal Vp corresponding to the current flowing between the detection electrode 4 and the ground portion 5 via the impedance circuit 6. In the present embodiment, the voltage generated in the resistance element 10 matches the voltage between the detection electrode 4 and the ground portion 5.

  In this case, the resistance value of the resistance element 10 of the impedance circuit 6 is detected as an abnormal discharge detected by a pulse signal, which will be described later, included in the voltage signal Vp when an abnormal discharge occurs between the discharge electrode 2 and the foreign object. The output generation circuit 7 is set so that the signal can be detected. The resistance value is set to about 3 kΩ, for example.

  The circuit configuration of the impedance circuit 6 is not limited to the configuration shown in FIG. For example, two or more resistance elements may be connected in series or in parallel. The impedance circuit 6 may output a voltage obtained by dividing the voltage between the detection electrode 4 and the ground portion 5 as the voltage signal Vp. Furthermore, the impedance circuit 6 may include, for example, a capacitive element in addition to the resistance element.

  The impedance circuit 6 basically has a voltage signal corresponding to a displacement current generated in the space between the discharge electrode 2 and the detection electrode 4 in accordance with a positive or negative high voltage applied to the discharge electrode 2. It is only necessary to be configured to output (a voltage signal including a frequency component in a higher frequency range than the frequency of the high voltage applied to the discharge electrode 2).

  The abnormal discharge detection output generation circuit 7 corresponds to the abnormal discharge detection means in the present invention. Here, before describing the specific configuration of the abnormal discharge detection output generation circuit 7, the voltage signal Vp output from the impedance circuit 6 will be described.

  When one of positive and negative high voltages, for example, a positive high voltage, is applied to the discharge electrode 2 from the high voltage generation circuit 3, an abnormal discharge occurs in the potential (measured value) of the discharge electrode 2 with respect to the ground portion 5. In the normal case where it does not, it changes as shown by the graph a1 in FIG.

  On the other hand, when an abnormal discharge such as a spark discharge occurs between the discharge electrode 2 and a foreign object during the application of a positive high voltage to the discharge electrode 2, the potential (measured value) of the discharge electrode 2 is It changes as shown by the graph a2 in FIG. That is, with the occurrence of abnormal discharge, the magnitude of the potential of the discharge electrode 2 suddenly decreases (approaches zero potential).

  Note that the change in potential of the discharge electrode 2 as described above is the same when a negative high voltage is applied to the discharge electrode 2. In this case, the potential of the discharge electrode 2 changes in a form in which the polarities of the graphs a1 and a2 in FIG. 5 are reversed.

  On the other hand, when a positive or negative high voltage is applied to the discharge electrode 2, depending on the capacitance between the discharge electrode 2 and the detection electrode 4, between the discharge electrode 2 and the detection electrode 4, A displacement current accompanying a change in potential of the discharge electrode 2 is generated, and a voltage is induced in the detection electrode 4 by the displacement current. Due to the induced voltage, a current corresponding to the displacement current (current having the same current value as the displacement current) flows between the detection electrode 4 and the ground portion 5 through the impedance circuit 6. As a result, a voltage signal Vp corresponding to the displacement current is output from the impedance circuit 6.

  At this time, in a normal state where no abnormal discharge has occurred, the voltage signal Vp changes almost smoothly in the same manner as the change in the potential of the discharge electrode 2, but when an abnormal discharge occurs, the discharge electrode 2 The displacement current also changes abruptly in response to the abrupt change in potential as described above. For this reason, the voltage signal Vp output from the impedance circuit 6 includes a steep pulse signal.

  For example, when the potential of the discharge electrode 2 changes as shown by a graph a2 in FIG. 5 due to the occurrence of abnormal discharge, the voltage signal Vp output from the impedance circuit 6 has a form as shown in FIG. The pulse signal resulting from abnormal discharge is included in the voltage signal Vp.

  Therefore, the abnormal discharge detection output generation circuit 7 of the present embodiment is a voltage signal input from the impedance circuit 6 in a state where one of positive and negative high voltages, for example, a positive high voltage is applied to the discharge electrode 2. It functions to detect the presence or absence of a pulse signal resulting from abnormal discharge from Vp.

  The abnormal discharge detection output generation circuit 7 having such a function will be specifically described below. In the present embodiment, the abnormal discharge detection output generation circuit 7 has a high-pass filter 11 to which the voltage signal Vp output from the impedance circuit 6 is input and the abnormal discharge from the output of the high-pass filter 11 as shown in FIG. When a signal corresponding to a pulse signal (pulse signal) that is included in the voltage signal Vp is detected, an output indicating the presence or absence of the pulse signal is used to determine whether or not abnormal discharge has occurred. And a pulse signal detector 12 that generates the output as shown.

  The high pass filter 11 corresponds to filtering means in the present invention. The high pass filter 11 cuts off a frequency component lower than a predetermined cut-off frequency in the voltage signal Vp input from the impedance circuit 6 and passes a frequency component higher than the cut-off frequency (high pass characteristic (high pass). Characteristic).

  In this case, the cut-off frequency of the high-pass filter 11 is set to a frequency higher than the high-voltage frequency output from the high-voltage generation circuit 3 (the frequency of the reciprocal value of the positive and negative high-voltage generation periods). .

  More specifically, the cutoff frequency is output from the high-pass filter 11 according to the voltage signal Vp output from the impedance circuit 6 when corona discharge of the discharge electrode 2 is normally performed without causing abnormal discharge. The magnitude of the signal (in particular, the signal of the fundamental frequency component of the reciprocal value of the application period of the high voltage to the discharge electrode 2 and the signal of the harmonic component that is an integral multiple of the fundamental frequency) is sufficiently small, and When the pulse signal resulting from abnormal discharge is included in the voltage signal Vp, the signal corresponding to the pulse signal is set to be output from the high-pass filter 11. In this embodiment, this cutoff frequency is set to about 30 kHz, for example.

  As such a high-pass filter 11, various types of circuit configurations can be employed. As an example, the high-pass filter 11 is configured by an analog filter (an analog filter including an amplifier circuit) as shown in FIG. 4, for example.

  The high-pass filter 11 is configured by connecting a capacitor 11a, a resistance element 11b, a transistor 11c, and a resistance element 11d as illustrated. The high-pass filter 11 extracts a high frequency component from the voltage signal Vp input from the impedance circuit 6 with the positive high voltage applied to the discharge electrode 2 via the capacitor 11a (cuts off the low frequency component). Then, by amplifying this high frequency component through the transistor 11c, a detection signal Vad indicating the high frequency component of the voltage signal Vp is output.

  For example, when the voltage signal Vp of the impedance circuit 6 is a voltage signal including a pulse signal as shown in FIG. 6A, the voltage at the position P1 in FIG. 4 (the input voltage to the base of the transistor 11c) is: As shown in FIG. 6B, the signal changes in a pulse shape. At this time, the detection signal Vad output from the high-pass filter 11 is a pulse-like signal corresponding to the pulse signal included in the voltage signal Vp, that is, a signal that changes in a pulse shape as shown in FIG. .

  In a state where no abnormal discharge has occurred, the detection signal Vad output from the high-pass filter 11 is a signal maintained at a voltage value of substantially zero level.

  Here, the voltage signal Vp output from the impedance circuit 6 generally includes a high-frequency noise component that can pass through the high-pass filter 11. However, such a noise component is usually a signal that instantly rises like a whisker. In FIGS. 6A to 6C, signal waveforms are shown in a form in which the noise components as described above are removed for the sake of easy understanding of the drawings.

  With respect to the noise component, a pulse signal that is included in the voltage signal Vp due to the occurrence of the abnormal discharge, and thus a pulse signal output from the high-pass filter 11 as a signal corresponding to the pulse signal is One or both of the peak value and the time width are usually larger than the noise component as described above.

  Therefore, the pulse signal detection unit 12 has a voltage value (peak value) greater than a predetermined value set in advance from the output (detection signal Vad) of the high-pass filter 11 and has a predetermined width set in advance. A pulse-like signal having the above time width is detected as a signal corresponding to a pulse signal that is included in the voltage signal Vp when an abnormal discharge occurs. Then, the pulse signal detector 12 outputs a signal Vout indicating whether or not the pulse-like signal is detected as the abnormal discharge detection signal Vout indicating whether or not the abnormal discharge is present. The pulse signal detector 12 corresponds to the pulse signal detector in the present invention.

  The pulse signal detector 12 having such a function can be realized by various and various circuit configurations. As an example, the pulse signal detection unit 12 includes a circuit as shown in FIG. The pulse signal detector 12 includes a Schmitt trigger circuit 12a to which an output (detection signal Vad) of the high-pass filter 11 is input, an integration circuit 12b that integrates the output of the Schmitt trigger circuit 12a, and an output of the integration circuit 12b. And an input Schmitt trigger circuit 12c.

  The Schmitt trigger circuit 12a corresponds to the width of the pulse-shaped signal when the output (detection signal Vad) of the high-pass filter 11 includes a pulse-shaped signal having a peak value larger than a predetermined value. A rectangular wave signal having a pulse width is output. For example, as shown in FIG. 6C, when the detection signal Vad includes a pulse signal corresponding to abnormal discharge, the output voltage of the Schmitt trigger circuit 12a (the voltage at the position P2 in FIG. 4). Becomes a rectangular wave signal as shown in FIG.

  The Schmitt trigger circuit 12a removes a noise component having a small peak value from the detection signal Vad.

  The integration circuit 12b for inputting the output of the Schmitt trigger circuit 12a is configured by connecting, for example, a variable resistance resistance element 12b1 and a capacitor 12b2 as shown in the figure. The integrating circuit 12b integrates the output (rectangular wave signal) of the Schmitt trigger circuit 12a with a predetermined time constant defined in accordance with the resistance value of the resistance element 12b1 and the capacitance value of the capacitor 12b2. The signal is output from the capacitor 12b2.

  For example, when a rectangular wave signal as shown in FIG. 6D is input from the Schmitt trigger circuit 12a to the integration circuit 12b, the output voltage of the integration circuit 12b (the voltage at the position P3 in FIG. 4) is: The signal is as shown in FIG.

  In other words, the integration circuit 12b is a low-pass filter.

  The Schmitt trigger circuit 12c, which receives the output of the integration circuit 12b, outputs a high-level rectangular wave signal when the output level (voltage value) of the integration circuit 12b exceeds a predetermined value, and outputs the output of the integration circuit 12b. When the level is smaller than a predetermined value, a low level signal is output.

  For example, when a signal as shown in FIG. 6 (e) is output from the integrating circuit 12b, a high-level rectangular wave signal as shown in FIG. 6 (f) is output from the Schmitt trigger circuit 12c.

  Thus, the signal output from the Schmitt trigger circuit 12c is the abnormal discharge detection signal Vout.

  Here, the fact that the output level of the integrating circuit 12b is equal to or higher than a predetermined value means that the pulse signal input to the Schmitt trigger circuit 12a has a voltage value (peak value) having a magnitude equal to or higher than the predetermined value. It means that the signal is a pulse signal having a time width equal to or greater than a predetermined width.

  Therefore, the pulse signal detection unit 12 has a voltage value (peak value) greater than or equal to a predetermined value and a pulse-shaped signal having a time width greater than or equal to a preset predetermined width by the above circuit configuration. Can be detected.

  For this reason, the abnormal discharge detection signal Vout output from the Schmitt trigger circuit 12c by the pulse signal detector 12 is obtained as a signal indicating whether or not the voltage signal Vp includes a pulse signal resulting from the occurrence of abnormal discharge. .

  In this embodiment, the output of the abnormal discharge detection output generation circuit 7 (the abnormal discharge detection signal Vout output from the pulse signal detection unit 12) is used for operation control of the high voltage generation circuit 3, and the abnormal discharge is detected. When the detection signal Vout becomes a high-level rectangular wave signal indicating the occurrence of abnormal discharge, the operation of the high voltage generation circuit 3 (high voltage output) is stopped accordingly.

  In this case, in addition to stopping the operation of the high voltage generation circuit 3, an operator such as an indicator (not shown) such as a display, a lamp, or a buzzer is notified that abnormal discharge has occurred. Also good.

  Supplementally, the circuit configurations of the high-pass filter 11 and the pulse signal detector 12 of the abnormal discharge detection output generation circuit 7 are not limited to those shown in FIG. It may be adopted.

  Instead of the high-pass filter 11, a band-pass filter having a high-frequency cutoff frequency in addition to the low-frequency cutoff frequency may be used. Further, the high-pass filter 11 may perform high-pass characteristic (or band-pass characteristic) filtering processing on the voltage signal Vp by digital processing such as FFT or software processing.

  Further, for example, the output of the high-pass filter 11 (or the band-pass filter) is detected as a digital value via the A / D converter, and abnormalities are detected from the detected digital value by software processing of an arithmetic processing unit having a CPU or the like. You may make it detect the presence or absence of the pulse signal resulting from discharge.

  The abnormal discharge detection output generation circuit 7 outputs a high level signal in a state where the pulse signal resulting from the occurrence of abnormal discharge is not included in the voltage signal Vp, and the pulse signal is included in the voltage signal Vp. In this case, a low level signal may be output.

  Next, the whole operation | movement regarding the detection of the abnormal discharge of the ion generator 1 of this embodiment is demonstrated.

  When neutralizing an object to be neutralized (charged object), the high voltage generation circuit 3 is activated, so that positive and negative high voltages are output from the output terminal 3a of the high voltage generation circuit 3 to the discharge electrode 2 at a constant cycle. Are alternately applied. In this case, the air supply mechanism also blows air. However, it is not essential to blow.

  At this time, in a period in which a positive or negative high voltage is applied to the discharge electrode 2, the discharge electrode 2 and the detection electrode 4 as a counter electrode are concentrated so as to concentrate on the tip of the discharge electrode 2. Corona discharge is generated from the tip of the discharge electrode 2 due to the electric field. And air ion is produced | generated by ionizing air by this corona discharge.

  In this case, positive air ions are generated by corona discharge in a state where a positive high voltage is applied to the discharge electrode 2, and negative air is generated by corona discharge in a state where a negative high voltage is applied to the discharge electrode 2. Air ions are generated.

  The charged charges of the object to be neutralized are neutralized by the positive and negative air ions thus generated, and the object to be neutralized is neutralized.

  During such operation, when corona discharge from the discharge electrode 2 is normally generated, the abnormal discharge detection output generation circuit 7 outputs the abnormal discharge detection output generation circuit 7 as described above. The abnormal discharge detection signal Vout is maintained as a signal (in this embodiment, a low level signal) indicating that no abnormal discharge has occurred.

  On the other hand, when any foreign object grounded (or connected to the ground portion) approaches or comes into contact with the discharge electrode 2, abnormal discharge occurs between the discharge electrode 2 and the foreign object.

  At this time, the voltage signal Vp output from the impedance circuit 6 includes a pulse signal resulting from the occurrence of abnormal discharge as described above.

  A pulse-like signal corresponding to this pulse signal is detected from the output (detection signal Vad) of the high-pass filter 11 by the above-described operation of the abnormal discharge detection output generation circuit 7, and from the abnormal discharge detection output generation circuit 7 An abnormal discharge detection signal Vout (in this embodiment, a high-level rectangular wave signal) indicating that an abnormal discharge has occurred is output.

  In response to this, the operation of the high voltage generation circuit 3 is stopped, and the application of positive and negative high voltages to the discharge electrode 2 is cut off.

  As described above, according to the present embodiment, when an abnormal discharge occurs between the discharge electrode 2 and the foreign object, the occurrence of the abnormal discharge can be detected with high reliability. Then, immediately after the detection, the application of positive and negative high voltages to the discharge electrode 2 is cut off to prevent the discharge electrode 2 from being damaged or rapidly deteriorated, or the high voltage generating circuit 3 from being damaged. be able to.

  Supplementally, abnormal discharge may occur between the output terminal 3a of the high voltage generation circuit 3 and a foreign object. Even in this case, the voltage signal Vp of the impedance circuit 6 includes a pulse signal resulting from the abnormal discharge, as in the case where the abnormal discharge occurs between the discharge electrode 2 and the foreign object. . Even in this case, the abnormal discharge detection output generation circuit 7 can detect the occurrence of the abnormal discharge.

  Next, some modifications of the embodiment of the present invention will be described.

  In the said embodiment, although the ion generator 1 in case the discharge electrode 2 was single was demonstrated to the example, the ion generator to which this invention is applied may be provided with the some discharge electrode 2. FIG.

  In that case, each discharge electrode 2 may be provided with a set of a detection electrode 4, an impedance circuit 6, and an abnormal discharge detection output generation circuit 7. However, for example, all the discharge electrodes 2 provided in the ion generator are N groups (N: integer of 2 or more) are grouped, and a single impedance circuit 6 and an abnormal discharge detection output generation circuit 7 are shared for N discharge electrodes 2 in each group. Also good.

  For example, as shown in FIG. 7, detection electrodes 4 arranged to face each of N (five in the illustrated example) discharge electrodes 2 belonging to one group are arranged in parallel with a single impedance circuit 6. The output (voltage signal Vp) of the impedance circuit 6 may be input to the abnormal discharge detection output generation circuit 7 similar to that of the above embodiment. In this case, the same high voltage is simultaneously applied to the N discharge electrodes 2 from the high voltage generation circuit 3.

  Even in this case, the voltage signal Vp output from the impedance circuit 6 includes a pulse signal resulting from the occurrence of abnormal discharge as in the above-described embodiment. Therefore, the abnormal discharge detection output generation circuit 7 can detect the pulse signal appropriately and detect the occurrence of abnormal discharge.

  In the example shown in FIG. 7, each of the N discharge electrodes 2 is provided with a detection electrode 4. However, the detection electrodes 4 are configured integrally to form the N discharge electrodes. 2 may be provided with a common detection electrode 4. In this case, the common detection electrode 4 is disposed, for example, on a plate-like conductor member having a plurality of through holes facing each discharge electrode 2 or on the side of the N discharge electrodes 2. It can comprise by the rod-shaped conductor member which was made.

  In the above embodiment, the abnormal discharge detection output generation circuit 7 has a pulse signal resulting from the occurrence of abnormal discharge in the voltage signal Vp of the impedance circuit 6 in a state where a positive high voltage is applied to the discharge electrode 2. Whether or not it is included is detected, but the voltage signal Vp of the impedance circuit 6 in a state where a negative high voltage is applied to the discharge electrode 2 includes a pulse signal resulting from the occurrence of abnormal discharge. It is also possible to detect whether or not

  Alternatively, in both the state where a positive high voltage is applied to the discharge electrode 2 and the state where a negative high voltage is applied, a pulse signal resulting from the occurrence of abnormal discharge is generated in the voltage signal Vp of the impedance circuit 6. You may make it detect whether it is contained.

  Moreover, in the said embodiment, although the ion generator (AC type ion generator) which applies a positive and negative high voltage alternately to the discharge electrode 2 was demonstrated as an example, the ion generator to which this invention is applied, It may be a direct current type ion generator that applies only a high voltage of one of positive and negative high voltages to the discharge electrode 2. Further, in this case, a direct current type ion generating apparatus may be provided that includes a discharge electrode that applies a positive high voltage and a discharge electrode that applies a negative high voltage.

  Also in these DC-type ion generators, with the same configuration as the ion generator of the above-described embodiment, an impedance circuit that connects the detection electrode facing the discharge electrode and the ground portion, an abnormal discharge detection output generator circuit, By providing, it is possible to detect the occurrence of abnormal discharge as in the above embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Ion production apparatus, 2 ... Discharge electrode, 4 ... Detection electrode, 5 ... Grounding part, 6 ... Impedance circuit, 7 ... Abnormal discharge detection output generation circuit (abnormal discharge detection means), 11 ... High pass filter (filtering means) , 12... Pulse signal detector (pulse signal detector).

Claims (7)

In an ion generator for generating corona discharge from the discharge electrode by applying a positive or negative high voltage to the discharge electrode, and generating air ions by the corona discharge,
A detection electrode disposed opposite the discharge electrode;
An impedance circuit that is connected between the detection electrode and the ground portion and outputs a voltage signal corresponding to a current flowing between the detection electrode and the ground portion;
An abnormal discharge detection means for detecting whether or not an abnormal discharge, which is a discharge generated between the discharge electrode and a foreign object other than the detection electrode, is input based on the voltage signal; Prepared,
The abnormal discharge detection means passes a high frequency component including a frequency component composing a pulse signal included in the voltage signal due to the occurrence of the abnormal discharge when the abnormal discharge occurs, and the high frequency component Filtering means for applying a filtering process to the voltage signal having a frequency pass characteristic for cutting off a low frequency component having a lower frequency, and a pulse for executing a process for detecting a signal corresponding to the pulse signal from the output of the filtering means Signal detection means, and configured to detect the occurrence of the abnormal discharge depending on whether or not a signal corresponding to the pulse signal is detected by the pulse signal detection means. Ion generator. The ion generator according to claim 1,
The pulse signal detection means outputs, from the output of the filtering means, a pulse signal having a voltage value greater than a predetermined value set in advance and a time width greater than a predetermined width set in advance. An ion generating apparatus configured to detect a signal corresponding to a signal. In the ion generator according to claim 1 or 2,
The ion generator is an ion generator that generates a corona discharge from the discharge electrode by applying a positive or negative high voltage to the discharge electrode at a constant period.
The ion generating apparatus, wherein the filtering means is configured so that the high-frequency component to be passed is a component having a frequency higher than at least a frequency corresponding to the certain period. In the ion generator according to any one of claims 1 to 3,
The ion generator is configured to block application of the high voltage to the discharge electrode when detecting that the abnormal discharge has occurred. In the ion generator according to any one of claims 1 to 4,
A plurality of the discharge electrodes, and one or more detection electrodes opposed to at least one group of N (N: an integer of 2 or more) discharge electrodes of the plurality of discharge electrodes,
One or more said detection electrodes facing the said N discharge electrodes are connected to the said single impedance circuit, The ion generator characterized by the above-mentioned. In the ion generator according to any one of claims 1 to 5,
The ion generating apparatus, wherein the detection electrode is arranged so as to function as a counter electrode that generates a corona discharge between the discharge electrode and the counter electrode. In an ion generating apparatus that generates a corona discharge from a discharge electrode by applying a positive or negative high voltage to the discharge electrode and generates air ions by the corona discharge, the discharge electrode is disposed so as to face the discharge electrode. A method for detecting the presence or absence of an abnormal discharge, which is a discharge generated between a foreign object other than the detected electrode,
An impedance circuit that is connected between the detection electrode and the grounding part and outputs a voltage signal corresponding to a current flowing between the detection electrode and the grounding part is used, and the abnormal discharge occurs when the abnormal discharge occurs. Filtering having a frequency pass characteristic that allows a high-frequency component including a frequency component composing a pulse signal included in the voltage signal to pass due to the occurrence of a discharge and blocks a low-frequency component having a frequency lower than the high-frequency component. Subjecting the voltage signal to processing;
A signal corresponding to the pulse signal is detected from the signal obtained by the filtering process, and the presence or absence of the abnormal discharge is detected depending on whether or not the signal corresponding to the pulse signal is detected. And an abnormal discharge detection method for an ion generator.

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