Ionisator

Abstract

Ionizer (10) which generates ions in the vicinity of an electrode (14) by applying a voltage to the electrode (14), comprising: a first DC voltage generation circuit (20a) which is configured to generate a DC voltage with positive polarity, a second DC voltage generation circuit (20b) configured to generate a DC voltage with negative polarity, a first resistor (22a) connected to an output side of the first DC voltage generation circuit (20a), a second resistor (22b) connected to an output side of the second DC voltage generation circuit (20b), and a switching unit (24) which connects the first resistor (22a) and the second resistor (22b) to the electrode (14) of the ionizer (10), wherein the first DC voltage generation circuit (20a) is configured to continuously generate the DC voltage with positive polarity, wherein the second DC voltage generation circuit (20b) is configured to continuously generate the DC voltage with negative polarity, wherein the switching unit (24) includes a first switch (28a) which can establish a connection between the first resistor (22a) and the electrode (14), and has a second switch (28b) that can establish a connection between the second resistor (22b) and the electrode (14) and wherein the first switch (28a) and the second switch (28b) are configured to be switched on in different time bands.

Description

[0001] The present invention relates to an ionizer which generates ions in the vicinity of an electrode by applying a voltage to the electrode.

[0002] Technologies described in JP H10 - 64 691 A, JP 2000 - 58 290 A and JP 2007 - 66 770 A involve generating ions near electrodes by applying high voltages to them. The generated ions are then released towards an object to be neutralized, thereby removing a static charge and neutralizing the object.

[0003] Specifically, JP H10-64691A describes how a high-frequency, high-voltage signal generated by a high-voltage oscillation circuit is fed to two dual voltage rectifier circuits. A positive-polarity DC high voltage, rectified by one of the dual voltage rectifier circuits, is applied to one of the electrodes via a resistor. A negative-polarity DC high voltage, rectified by the other of the dual voltage rectifier circuits, is applied to the other electrode via a different resistor.

[0004] Furthermore, JP 2000 - 58 290 A describes a technique in which a series circuit with a positive-polarity high-voltage generator and a resistor, and a series circuit with a negative-polarity high-voltage generator and a resistor, are connected in parallel to an individual electrode. By alternately activating the positive-polarity high-voltage generator and the negative-polarity high-voltage generator, positive and negative DC voltages are alternately generated and applied to the electrode.

[0005] Furthermore, JP 2007 - 66 770 A describes a technique in which a series circuit with a positive-polarity high-voltage generator and a semiconductor switch, and a series circuit with a negative-polarity high-voltage generator and a semiconductor switch, are connected in parallel to an individual electrode. In this case as well, alternating operation of the positive-polarity high-voltage generator and the semiconductor switch, as well as the negative-polarity high-voltage generator and the semiconductor switch, alternately generates positive-polarity and negative-polarity DC voltages and applies them to the electrode.

[0006] On the other hand, JP H10 - 108 480 A describes a high-voltage switching circuit that can be used in an ionizer. This high-voltage switching circuit consists of a positively polarized DC voltage source and a negatively polarized DC voltage source, as well as four semiconductor switching elements. By controlling the on and off times of the respective semiconductor switching elements, a positively polarized DC voltage and a negatively polarized DC voltage are alternately applied to a load.

[0007] DE 10 2007 049 529 A1 and US 2007 / 0 279 829 A1 disclose an electrode device for the contactless removal of an electrostatic charge from a material. Summary of the invention

[0008] In the ionizer according to JP 2000 - 58 290 A, two resistors are connected in parallel to the electrode. If a DC voltage is applied to the electrode by one of the circuits generating a high DC voltage and the resistor, it is possible that some of the current flowing through one resistor will flow through the other resistor into the other circuit generating a high DC voltage. Consequently, the actual voltage applied to the electrode will be lower than the DC voltage generated by the first circuit. For example, assuming both resistors have the same resistance value, the voltage applied to the electrode will be only half the DC voltage.As a result, the efficiency with which ions are generated near the electrode decreases noticeably, and the ability of the ionizer to remove charges that charge the object to be neutralized is significantly reduced.

[0009] In light of this problem, it can be considered to compensate for and balance the decrease in the voltage applied to the electrode, and thus ensure charge removal capability, by increasing the voltage level of the DC voltage generated by the circuit for generating a high DC voltage. However, if the DC voltage is increased, the amount of heat generated (Joule heating) by the currents flowing in the two resistors also increases, and the temperature of the ionizer housing containing the circuits for generating the high DC voltages rises. This is disadvantageous.

[0010] The same problem occurs when the DC voltage is applied to the electrode via the other circuit to generate a DC high voltage and the resistance.

[0011] It is also possible to overcome the problems described above by means of a configuration that does not use resistors. This is the case, for example, with the ionizer according to JP 2007 - 66 770 A.

[0012] The resistors in the JP 2000 - 58 290 A serve as current-limiting protective resistors, designed to protect the circuits that generate the high-voltage DC current. Without these protective resistors, the circuits generating the high-voltage DC current cannot be adequately protected.

[0013] In the techniques described in JP 2000 - 58 290 A and JP 2007 - 66 770 A, a DC voltage of positive polarity and a DC voltage of negative polarity are applied alternately to a single electrode by alternately operating one of the circuits for generating the DC high voltage (and the semiconductor switching element) and the other circuit for generating the DC high voltage (and the semiconductor switching element).When the circuits for generating the DC high voltage that supply the electrode with DC voltages are switched, or in particular when one circuit for generating the DC high voltage (and switching on the semiconductor switching element) is activated together with the discontinuation of the other circuit for generating the DC high voltage (and switching off the semiconductor switching element), the time required to start the operation of the one circuit for generating the DC high voltage, whose activation is to begin, and the time required to switch off the other circuit for generating the DC high voltage, whose operation is to be stopped, are delayed by the resistances and stray capacitance or by the capacitors of the circuits for generating the DC high voltage and the line resistance.As a result, the time required for the voltages applied to the electrode to reach a voltage value necessary for ion generation is delayed, and contrary to expectations, the charge removal capability is impaired.

[0014] Furthermore, the same problems are highly likely to occur if the operation of one circuit for generating a DC high voltage is interrupted when the operation of the other circuit for generating a DC high voltage is started.

[0015] The object of the present invention is to create an ionizer which improves the charge removal (neutralization) capability by controlling the heat generation of resistors connected to the output sides of the high DC voltage generation circuits and by reducing the switching times of the two high DC voltage generation circuits and improving their response speed.

[0016] This problem is solved by the invention through the features of claim 1.

[0017] Advantageous embodiments of the invention are set out in the dependent claims.

[0018] To solve the above-mentioned problem, the ionizer according to the present invention comprises a first circuit for generating a DC voltage, which generates a DC voltage with positive polarity (positive DC voltage), a second circuit for generating a DC voltage, which generates a DC voltage with negative polarity (negative DC voltage), a first resistor connected to an output side of the first DC voltage generation circuit, a second resistor connected to an output side of the second DC voltage generation circuit, and a switching unit which connects the first resistor and the second resistor to the electrode.

[0019] In this case, the first DC voltage generation circuit continuously generates the positive DC voltage, the second DC voltage generation circuit continuously generates the negative DC voltage, the switching unit has a first switch that is able to establish a connection between the first resistor and the electrode, and a second switch that is able to establish a connection between the second resistor and the electrode, with the first switch and the second switch being turned on at different time intervals.

[0020] The terms “continuous generation of DC voltage with positive polarity” and “continuous generation of DC voltage with negative polarity” mean that during operation of the ionizer, and in particular during a period in which the removal of a static charge from an object to be neutralized is carried out with the aid of the ionizer, the first DC voltage generation circuit continues to output a DC voltage with positive polarity and that the second DC voltage generation circuit continues to output a DC voltage with negative polarity.

[0021] Accordingly, according to the present invention, the first DC voltage generation circuit and the second DC voltage generation circuit are normally in an operating state (i.e., in a energized state). Therefore, when the first switch or the second switch is turned ON, the positive DC voltage generated by the first DC voltage generation circuit or the negative DC voltage generated by the second DC voltage generation circuit can be applied to the electrode without modification.

[0022] Since the first and second switches are turned on at different times, a current flowing through the first resistor can be prevented from flowing through the second resistor into the second DC voltage generation circuit. Conversely, a current flowing through the second resistor can be prevented from flowing through the first resistor into the first DC voltage generation circuit.

[0023] In this way, the value of the voltage applied to the electrode becomes either the value of the DC voltage with positive polarity or the value of the DC voltage with negative polarity. Therefore, it is not necessary to increase the DC voltage to compensate for a voltage drop, as is the case in Japanese patent publication JP 2000-58290A. Accordingly, the first DC voltage generation circuit and the second DC voltage generation circuit are capable of reducing the DC voltage to a voltage value necessary for generating ions near the electrode.Specifically, the present invention allows the DC voltage values ​​generated by the first DC voltage generation circuit and the second DC voltage generation circuit to be reduced compared to the disclosure in Japanese patent publication JP 2000 - 58 290 A, while still maintaining and ensuring the ability of the ionizer to remove a charge.

[0024] As a result, the current flowing through the first and second resistors is reduced, thus lowering power consumption. Simultaneously, the heat generated by the first and second resistors is also reduced. Consequently, an increase in the temperature of the ionizer housing, which contains the first and second DC voltage generation circuits, can be avoided.

[0025] The first and second switches of the switching unit also switch the voltage supplied to the electrode between a positive DC voltage and a negative DC voltage. Therefore, the timing with which the first and second DC voltage generation circuits are switched relative to the electrode (i.e., the timing with which the positive and negative DC voltages are switched) depends on the switching times of the first and second switches. By using switching elements with high response speeds as the first and second switches, whose dielectric strength is higher than the positive and negative DC voltages, the switching time can be easily reduced.

[0026] As described above, in the present invention, the first DC voltage generation circuit continuously generates a DC voltage with positive polarity, and the second DC voltage generation circuit continuously generates a DC voltage with negative polarity. When the first and second switches are turned on and off, either the positive or negative DC voltage can be applied directly to the electrode. As a result of the switching action of the first and second switches, the voltage applied to the electrode is rapidly changed to either a positive or negative DC voltage. This reduces the switching time.Since the voltage applied to the electrode can be quickly changed to a positive DC voltage or a negative DC voltage, the ability of the ionizer to remove a charge can be improved.

[0027] By continuously generating the positive DC voltage and the negative DC voltage, and by shortening the switching time, it is possible to prevent the discharge time of the first DC voltage generation circuit or the second DC voltage generation circuit and the switch-on time of the first DC voltage generation circuit or the second DC voltage generation circuit from being affected by the first resistor, the second resistor and the stray capacitance, or by the capacitors of the first DC current generation circuit and the second DC current generation circuit and the line resistance.

[0028] In this way, the present invention allows heat generation in the first and second resistors to be avoided by inserting the switching unit between the electrode and the second resistor. Simultaneously, the switching time can be reduced and the response speed improved. As a result, the charge removal capability of the ionizer can be enhanced.

[0029] The ionizer can include a switching control circuit for controlling the on and off times of the first and second switches, wherein the first and second switches are preferably semiconductor switching elements that are switched on or off by control signals supplied by the switching control circuit. Semiconductor switching elements (for example, silicon transistors with a voltage rating on the order of 4000 V) include current-output transistors, FETs (field-effect transistors), or MOSFETs (metal-oxide-semiconductor FETs) and are capable of high-speed responses. Therefore, the aforementioned effect of reducing the switching time can be easily achieved.

[0030] Furthermore, the first DC voltage generation circuit and the second DC voltage generation circuit are preferably Cockcroft-Walton circuits, formed, for example, by capacitors and diodes arranged as a multi-stage rectifier circuit in which the capacitors are stacked in series.

[0031] To reduce the DC voltage to the voltage required for generating ions near the electrode, the number of capacitor stages in the Cockcroft-Walton circuits can simply be reduced. Accordingly, when using Cockcroft-Walton circuits, the voltage values ​​generated by the first and second DC voltage generation circuits can be reduced.

[0032] For use as a first generation circuit and as a second generation circuit, different types of circuits for generating a DC high voltage can also be used instead of Cockcroft-Walton circuits, such as double voltage rectifier circuits or the like.

[0033] Furthermore, the ionizer mentioned above can include an AC voltage generation circuit that generates an alternating voltage and a transformer whose primary winding is connected to the AC voltage generation circuit. In this case, (1) as groups, each formed by an AC voltage generation circuit and a transformer, the first DC voltage generation circuit is connected to a secondary winding of a transformer in one group, and the second DC voltage generation circuit is connected to a secondary winding of a transformer in another group. Alternatively, (2) the first DC voltage generation circuit and the second DC voltage generation circuit are both connected to the secondary winding of the transformer in one group.

[0034] In both cases described above (1) and (2), the AC voltage generation circuit preferably generates the AC voltage continuously. If the AC voltage is generated continuously in this way, it is possible to generate the positive DC voltage and the negative DC voltage continuously.

[0035] In comparison to the circuit configuration of case (1) above, the AC voltage generation circuit and the transformer can be reduced by one group in the circuit configuration of case (2), thus simplifying the circuit configuration. This allows the ionizer to be manufactured at a lower cost. Conversely, in the ionizer with the circuit configuration according to case (1), if one of the AC voltage generation circuit and transformer groups is damaged, the circuit configuration can be changed to the configuration according to case (2) by using the other AC voltage generation circuit and transformer group, and the ionizer can continue to be used.

[0036] Preferably, the AC voltage generation circuit comprises a DC-AC converter which converts an input DC voltage into the AC voltage and then outputs the AC voltage to the primary winding of the transformer.

[0037] Further developments, advantages and application possibilities of the invention also result from the following description of an exemplary embodiment and the drawing. Brief description of the drawings Fig. Figure 1 is a circuit diagram of an ionizer according to an embodiment of the present invention. Fig. 2 is a circuit diagram of a modification of the ionizer according to Fig. 1, Fig. Figure 3 is a circuit diagram of an ionizer according to a comparative example and Fig. Figure 4 is a time diagram showing, for the present embodiment and the comparative example, the times at which an output voltage applied to a needle electrode is changed. Description of preferred embodiments

[0038] A preferred embodiment of an ionizer according to the present invention will now be described in detail with reference to the accompanying drawings.

[0039] As in Fig. As shown in Figure 1, an ionizer 10 according to the present embodiment is formed by a generator 12 for generating a direct current high voltage (DC generator) and a needle electrode 14, onto which the generated direct current high voltage (output voltage) V is applied. out is applied. When the output voltage V out When a substance is applied to the needle electrode 14, ions are generated in the vicinity of the needle electrode 14. When the generated ions are released towards an object that is to be neutralized (i.e., an object from which static charges are to be removed), electrical charges accumulated in the object can be neutralized and the static charge can be removed from the object to be neutralized.

[0040] The DC voltage generator 12 comprises a voltage generator 12a of positive polarity (positive voltage generator) which produces an output voltage with positive polarity +V out (which is a direct current high voltage with positive polarity, which for the sake of simplicity will subsequently be referred to as "positive voltage +V") out “ is designated), and a voltage generator 12b of negative polarity (negative voltage generator) which produces an output voltage with negative polarity -V out generated (which is a direct current high voltage with negative polarity, which for the sake of simplicity will subsequently be referred to as "negative voltage -V") out “ is designated).

[0041] The positive voltage generator 12a comprises a voltage drive circuit 16a (circuit for generating an alternating current voltage), which acts as a DC-AC converter for converting a direct current voltage V in(DC input voltage) into an AC voltage, a transformer 18a for boosting or amplifying the AC voltage generated by the voltage drive circuit 16a, and a circuit 20a for generating a DC high voltage (first DC voltage generation circuit), which rectifies the boosted AC voltage and the positive voltage +V out generated.

[0042] The negative voltage generator 12b comprises a voltage drive circuit 16b (circuit for generating an alternating voltage), which acts as a DC-AC converter for converting a direct current voltage V in(DC input voltage) into an AC voltage, a transformer 18b for boosting or increasing the AC voltage generated by the voltage drive circuit 16b, and a circuit 20b for generating a DC high voltage (second DC voltage generation circuit), which rectifies the boosted AC voltage and the negative voltage -V out generated.

[0043] The DC voltage generation circuits 20a, 20b are preferably Cockcroft-Walton circuits, formed, for example, by capacitors and diodes arranged as a multi-stage rectifier circuit, with the capacitors stacked in series. Alternatively, dual voltage rectifier circuits can be used. Both cases are suitable provided the DC voltage generation circuits are capable of converting an AC voltage into a DC high voltage.

[0044] An output resistor 22a (first resistor), which serves as a current-limiting resistor to protect the circuit of the positive voltage generator 12a, is connected to the output side of the DC voltage generation circuit 20a. An output resistor 22b (second resistor), which serves as a current-limiting resistor to protect the circuit of the negative voltage generator 12b, is connected to the output side of the DC voltage generation circuit 20b.

[0045] A switching unit 24 is provided between the needle electrode 14 and the output resistors 22a, 22b. A switching control circuit 26 controls the switching unit 24. The switching unit 24 comprises a first switch 28a, which can establish an electrical connection between the output resistor 22a and the needle electrode 14, and a second switch 28b, which can establish an electrical connection between the output resistor 22b and the needle electrode 14. The first switch 28a and the second switch 28b are preferably semiconductor switching elements (for example, silicon transistors with a voltage rating on the order of 4000 V) and comprise transistors, FETs, MOSFETs, or the like, which are switched on and off by control signals supplied by the switching control circuit 26. In the drawing, reference numeral 30 denotes a connection point between the needle electrode 14 and the first and second switches 28a, 28b.

[0046] Accordingly, if the switching control circuit 26 supplies a control signal to the first switch 28a, the first switch 28a is turned on, and a conductive connection is established between the DC voltage generation circuit 20a, the output resistor 22a, and the needle electrode 14. Conversely, if the switching control circuit 26 supplies a control signal to the second switch 28b, the second switch 28b is turned on, and a conductive state is established between the DC voltage generation circuit 20b, the output resistor 22b, and the needle electrode 14.

[0047] As noted above, the construction from the voltage drive circuit 16a to the transformer 18a in the positive voltage generator 12a and the construction from the voltage drive circuit 16b to the transformer 18b in the negative voltage generator 12b are essentially identical. Therefore, in the present embodiment, as shown in Fig. As shown in Figure 2, a configuration can also be chosen in which a single voltage drive circuit 16 and a single transformer 18 are used together with the positive voltage generator 12a and the negative voltage generator 12b, with the DC voltage generation circuits 20a, 20b being connected in parallel to the second winding of the transformer 18.

[0048] The ionizer 10 according to the present embodiment is essentially constructed as described above. The operating mode of the ionizer 10 will be explained next.

[0049] Fig. Figure 3 is a circuit diagram of an ionizer 40 according to a comparative example, which differs from the ionizer 10 according to the present embodiment (compare Fig. 1 and Fig. 2) differs in that the switching unit 24 and the switching control circuit 26 are not provided between the needle electrode 14 and the output resistors 22a, 22b.

[0050] Fig. Figure 4 is a timing diagram to illustrate the operation of the ionizer 10 according to the present embodiment and the ionizer 40 according to the comparative example, and in particular to illustrate the operations by which output voltages V out , V out ' will be issued.

[0051] In the ionizer 10 according to the present embodiment, if static charges are to be removed from an object (not shown) that is to be neutralized, a direct voltage V is applied. inThe voltage is continuously supplied to the voltage drive circuits 16, 16a, 16b. Accordingly, the voltage drive circuits 16, 16a, 16b, which function as DC-AC converters, convert the DC voltage V. in The AC voltage is converted into an AC voltage, and this AC voltage is supplied to the primary winding of transformers 18, 18a, 18b. Transformers 18, 18a, 18b amplify the AC voltage supplied to their primary windings, and after amplification, the amplified AC voltage is supplied to the DC high-voltage generation circuits 20a, 20b.

[0052] During the operation of the ionizer 10, and in particular for carrying out the removal of static charges from the object to be neutralized, the DC voltage V is generated during the period in which the DC voltage generation circuits 20a, 20b generate the DC voltage. incontinuously supplying voltage to the voltage drive circuits 16, 16a, 16b, continuously performing operations to convert the amplified AC voltage on the secondary winding side of the transformers 18, 18a, 18b into the positive voltage +V out or the negative voltage -V out to convert and output this voltage to the output resistors 22a, 22b.

[0053] In Fig. Figure 4 shows an example of a case in which the DC voltage generation circuit 20a continuously generates a positive voltage +V out outputs a voltage value of +Va and the DC voltage generation circuit 20b continuously outputs a negative voltage -V out outputs a voltage value of -Va.

[0054] The switching control circuit 26 outputs at fixed time intervals (in Fig. 4 T / 2) alternately sends control signals to the first switch 28a and the second switch 28b to turn on its transistor, FET, or MOSFET. Within the time period T, the first switch 28a and the second switch 28b are accordingly turned on alternately at the corresponding times T / 2. Specifically, within the time period T, in a time band defined by the first half T / 2 of the time period T, the first switch 28a is turned on and the second switch 28b is turned off. In a time band defined by the second half T / 2 of the time period T, the second switch 28b is turned on and the first switch 28a is turned off.

[0055] As a result, during the time band in which the first switch 28a is switched on, the DC voltage generation circuit 20a can generate the positive voltage +V outwith a voltage value of +Va applied across the output resistor 22a, the first switch 28a and the connection point 30 to the needle electrode 14. On the other hand, during the time band in which the second switch 28b is switched on, the DC voltage generation circuit 20b can apply the negative voltage -V out with a voltage value of -Va applied to the needle electrode 14 via the output resistor 22b, the second switch 28b and the connection point 30.

[0056] Accordingly, as in Fig. As shown in section 4, the output voltage is V out The DC voltage applied to the needle electrode 14 is a square wave DC voltage that switches between voltage values ​​+Va and -Va after each time period T / 2. As discussed above, the DC voltage generation circuits 20a and 20b provide the positive voltage +Va during operation of the ionizer 10. out or the negative voltage -V outcontinues to be off. Therefore, the time (switching time) required for the voltage polarity of the output voltage V depends on out , which is to be switched, is required, from the switching times of the first switch 28a and the second switch 28b.

[0057] The first switch 28a and the second switch 28b are semiconductor switching elements, such as transistors, FETs, MOSFETs, or the like. For this reason, the switching times are relatively short, so that the switching time required to reverse the polarity of the output voltage V is out The required length can be easily shortened. Accordingly, the polarity of the output voltage V can be changed. out can be switched quickly.

[0058] During the time band in which the positive voltage +V out When a negative voltage is applied to the needle electrode 14, positive ions are generated near the needle electrode 14, whereas during the time band in which the negative voltage -V is applied, outWhen a substance is applied to the needle electrode 14, negative ions are generated near the needle electrode. Accordingly, by releasing the generated positive or negative ions to the object to be neutralized, the ionizer 10 can remove static charges that charge the object. The object can then be neutralized.

[0059] In contrast, the ionizer 40 according to the comparison example does not include the switching unit 24 and the switching control circuit 26. Therefore, for example, the supply of the DC voltage V can be considered during any period T / 2. in to repeatedly allow and stop the voltage drive circuits 16a, 16b, thereby changing the polarity between the positive output voltage +V out ' and the negative output voltage -V out ' can be switched.

[0060] However, in such a switching method, the output voltage V out The voltage applied to the needle electrode 14 is damped by a time delay caused by the output resistors 22a, 22b and stray capacitance, or by a time delay caused by the capacitors of the DC voltage generation circuit 20a, 20b, and the line resistance. As a result, the time required to reach the voltage necessary to generate positive or negative ions near the needle electrode 14 is increased. The efficiency with which positive or negative ions are generated decreases, and the charge removal capability of the ionizer 40 deteriorates.

[0061] In contrast to the comparison example, the positive voltage +V is applied to the ionizer 10 according to the present embodiment. out and the negative voltage -V outThe DC voltage generation circuits 20a and 20b continuously output a DC voltage, and the switching unit 24 and the switching control circuit 26 are used to switch the conductive connection between the needle electrode 14 and the DC voltage generation circuits 20a and 20b. This allows the polarity of the output voltage V to be changed at any given time interval T / 2. outThe voltage applied to the needle electrode 14 can be switched rapidly. Assuming that the voltage values ​​+Va, -Va are greater than the values ​​required to generate positive or negative ions near the needle electrode 14, positive or negative ions can be reliably generated essentially within the time period T / 2. As a result, the ion generation efficiency of positive or negative ions can be improved, and the charge removal capability of the ionizer 10 (i.e., its ability to neutralize static charge) can be enhanced.

[0062] As described above, in the ionizer 10 according to the present embodiment, the DC voltage generation circuits 20a, 20b are always in an operating state (switched on state) during operation of the ionizer 10 (while the removal of static charge from an object to be neutralized is being carried out). Thus, when the first switch 28a or the second switch 28b is switched on, the positive voltage +V can be generated. out , which is generated by the DC voltage generation circuit 20a, or the negative voltage -V out , which is generated by the DC voltage generation circuit 20b, can be applied to the needle electrode 14 without modification.

[0063] Furthermore, the first switch 28a and the second switch 28b are switched on in different time bands. This prevents current flowing into the output resistor 22a from flowing via the output resistor 22b into the DC voltage generation circuit 20b, or vice versa.

[0064] In this way the value of the output voltage V is out , which is applied to the needle electrode 14, the value (+Va, -Va) of the positive voltage +V out or the negative voltage -V outFor this reason, it is not necessary to increase the DC voltage to compensate for a voltage drop, as is the case in Japanese patent publication JP 2000-58290A. Accordingly, the DC voltage generation circuits 20a and 20b are capable of generating the positive voltage +V out and the negative voltage -V out to reduce the voltage to values ​​required to generate positive or negative ions near the needle electrode 14. Specifically, in the present embodiment, compared to the disclosure in Japanese patent publication JP 2000-58290A, the values ​​of the positive voltage +V can be out and the negative voltage -V out , which are generated by the DC voltage generation circuits 20a, 20b, are reduced, while maintaining and ensuring the charge removal capability of the ionizer 10.

[0065] As a result, the currents flowing through the output resistors 22a and 22b decrease, thereby reducing the power consumption of the ionizer 10. The amount of heat generated by the output resistors 22a and 22b is also reduced. Consequently, an increase in the temperature of the ionizer 10 housing, which contains the DC voltage generation circuits 20a, 20b, or the like, can be avoided.

[0066] By switching the first switch 28a and the second switch 28b of the switching unit 24 on and off, the output voltage V supplied to the needle electrode 14 is also changed. out between the positive voltage +V out and the negative voltage -V outswitched. This affects the time at which the DC voltage generation circuit 20a and the DC voltage generation circuit 20b are switched with respect to the needle electrode 14 (i.e., the time at which the positive voltage +V out and the negative voltage -V out (with respect to the needle electrode 14 being switched), from the switching times of the first switch 28a and the second switch 28b. By using high-response semiconductor switching elements, such as transistors, FETs, MOSFETs or the like, as the first switch 28a and as the second switch 28b, whose voltage ratings are higher than the positive voltage +V out and the negative voltage -V out , the switching time can therefore be easily reduced.

[0067] As described above, in the present embodiment, the DC voltage generation circuits 20a, 20b also continuously generate the positive voltage +V during operation of the ionizer 10. out and the negative voltage -V out . Therefore, when the first switch 28a and the second switch 28b are switched on and off, the positive voltage +V can out or the negative voltage -V out directly to the needle electrode 14. Specifically, the value of the output voltage V is changed as a result of switching on and off using the first switch 28a and the second switch 28b. out , which is applied to the needle electrode 14, very quickly to the positive voltage +V out or the negative voltage -V out changed. In this way the switching time is shortened, and since the voltage value applied to the needle electrode 14 quickly becomes the positive voltage +V outor the negative voltage -V out By modifying the settings, the charge removal capability of the ionizer 10 can be improved.

[0068] By continuously generating the positive voltage +V out and the negative voltage -V out and by shortening the switching time it can also be prevented that the time to switch off the DC voltage generation circuits 20a, 20b and the time to switch on the DC voltage generation circuits 20a, 20b is affected by the output resistances 22a, 22b and the stray capacitance, or that they are affected by the capacitors of the DC voltage generation circuits 20a, 20b and the line resistance.

[0069] In this embodiment, by inserting the switching unit 24 and the switching control circuit 26 between the needle electrode 14 and the output resistors 22a, 22b, the heat generation in the output resistors 22a, 22b can be reduced, while simultaneously shortening the switching time and improving the response time. As a result, the charge removal capability of the ionizer 10 can be improved.

[0070] In the case that the DC voltage generation circuits 20a, 20b are Cockcroft-Walton circuits, to reduce the output voltage V outFurthermore, to enable the generation of positive or negative ions near the needle electrode 14 at a voltage required for this purpose, the number of capacitor stages in the Cockcroft-Walton circuits can be easily reduced (for example, the circuits can be changed from seven-stage to four-stage circuits). In this way, the values ​​of the positive voltage +V can be adjusted by using Cockcroft-Walton circuits. out and the negative voltage -V out , which are generated by the DC voltage generation circuits 20a, 20b, are simply reduced.

[0071] Furthermore, during the in Fig. 2 modified embodiment shown compared to the configuration according to Fig. 1. The arrangement consisting of the voltage drive circuit and the transformer can be reduced by one group. This simplifies the circuit design, and the ionizer 10 can be manufactured at a lower cost. On the other hand, in the configuration according to Fig. 1. In the event that one of the voltage drive circuit and transformer groups is damaged, the circuit configuration can be restored to that described in the diagram by using the other voltage drive circuit and transformer group. Fig. The configuration shown in section 2 can be changed and the ionizer 10 can continue to be used.

Claims

[1] Ionizer (10) which generates ions in the vicinity of an electrode (14) by applying a voltage to the electrode (14), comprising: a first DC voltage generation circuit (20a) which is configured to generate a DC voltage with positive polarity, a second DC voltage generation circuit (20b) configured to generate a DC voltage with negative polarity, a first resistor (22a) connected to an output side of the first DC voltage generation circuit (20a), a second resistor (22b) connected to an output side of the second DC voltage generation circuit (20b), and a switching unit (24) which connects the first resistor (22a) and the second resistor (22b) to the electrode (14) of the ionizer (10), wherein the first DC voltage generation circuit (20a) is configured to continuously generate the DC voltage with positive polarity, wherein the second DC voltage generation circuit (20b) is configured to continuously generate the DC voltage with negative polarity, wherein the switching unit (24) includes a first switch (28a) which can establish a connection between the first resistor (22a) and the electrode (14), and has a second switch (28b) that can establish a connection between the second resistor (22b) and the electrode (14) and wherein the first switch (28a) and the second switch (28b) are configured to be switched on in different time bands. [2] Ionizer (10) according to claim 1, further comprising a switching control circuit (26) for controlling the switching on and off times of the first switch (28a) and the second switch (28b), wherein the first switch (28a) and the second switch (28b) are semiconductor switching elements which are configured to be switched on and off by control signals supplied by the switching control circuit (26). [3] Ionizer (10) according to claim 1 or 2, characterized by , that the first DC voltage generation circuit (20a) and the second DC voltage generation circuit (20b) are Cockcroft-Walton circuits. [4] Ionizer (10) according to any of the preceding claims, further comprising an AC voltage generation circuit (16, 16a, 16b) configured to generate an AC voltage, and a transformer (18, 18a, 18b) whose primary winding is connected to the AC voltage generation circuit (16, 16a, 16b), wherein, as groups formed by an AC voltage generation circuit (16, 16a, 16b) and a transformer (18, 18a, 18b), the first DC voltage generation circuit (20a) is connected in one group to a secondary winding of a transformer (18a), and wherein in another group the second DC voltage generation circuit (20b) is connected to a secondary winding of a transformer (18b), or wherein alternatively the first DC voltage generation circuit (20a) and the second DC voltage generation circuit (20b) are connected together with the secondary winding of the transformer (18) in one group, and wherein the AC voltage generation circuit (16, 16a, 16b) is configured to continuously generate the AC voltage. [5] Ionizer (10) according to claim 4, characterized by, that the AC voltage generation circuit (16, 16a, 16b) has a DC-AC converter which is configured to convert a DC input voltage into an AC voltage and output the AC voltage to the primary winding of the transformer (18, 18a, 18b).

Images