JP4931192B2 - Static eliminator - Google Patents

Description

  The present invention relates to a static eliminator that generates positive and negative ions by applying a voltage to each of a pair of discharge electrodes to cause corona discharge.

  In the following Patent Document 1, a pair of discharge electrodes is provided, a negative voltage is applied to one discharge electrode to generate negative ions by corona discharge, and a positive voltage is applied to the other discharge electrode. In this method, positive ions are generated by corona discharge and neutralized by spraying the positive and negative ions onto a charged body.

  In this type of static eliminator, for example, dust in the surrounding air adheres to the discharge electrode, or the tip of the discharge electrode wears out due to long-term use, so that the discharge amount of ions from the discharge electrode decreases, There may be an abnormal state where the sufficient charge removal effect cannot be obtained (charge removal failure). In addition, the ion balance between positive ions and negative ions is lost due to the influence of the ambient temperature or the like, and a sufficient static elimination effect may not be obtained. Therefore, it is necessary to monitor each discharge amount (ion generation amount) of positive ions and negative ions.

Therefore, in the static eliminator of Patent Document 1 below, a positive ion detection electrode is provided for a positive discharge electrode that generates positive ions, and a negative ion detection electrode is provided for a negative discharge electrode that generates negative ions. It has been. Then, the amount of negative ions is monitored based on the load voltage level of the current measurement resistor provided between the negative ion detection electrode and the ground line, and the current measurement provided between the positive ion detection electrode and the ground line is measured. The discharge amount of positive ions is monitored based on the load voltage level of the resistor for use.
JP 2001-217094 A

  However, the technique disclosed in Patent Document 1 requires a plurality of ion detection electrodes (counter electrodes) corresponding to the respective discharge electrodes, and there is a problem that the arrangement and wiring of the counter electrodes in the static eliminator are complicated.

  The present invention has been completed based on the above-described circumstances, and an object thereof is to provide a static eliminator capable of monitoring the discharge amount of ions while suppressing the arrangement configuration of the counter electrode and the complexity of the wiring. There is a place to do.

As a means for achieving the above object, a static eliminator according to claim 1 applies a negative voltage to a pair of discharge electrodes and one of the pair of discharge electrodes. A negative voltage application circuit for generating negative ions, a positive voltage application circuit for generating positive ions by applying a positive voltage to the other discharge electrode, and the pair of discharge electrodes. A common counter electrode, a current measurement unit that outputs a measurement signal corresponding to the current flowing through the counter electrode, and always drives both the negative voltage application circuit and the positive voltage application circuit to drive the pair The negative voltage application circuit and the negative voltage application circuit in a period shorter than each continuous execution period of the neutralization operation when a predetermined measurement timing arrives while performing a neutralization operation of a direct current method that generates positive and negative ions from the discharge electrodes of Positive voltage sign A control unit that selectively stops driving of one of the application circuits, and a discharge state of a discharge electrode by the other application circuit based on the measurement signal output from the current measurement unit at the measurement timing. A discharge monitoring unit that monitors the change.

  According to a second aspect of the present invention, in the static eliminator according to the first aspect of the present invention, the static neutralizer includes a timing generation unit that generates the measurement timing at predetermined time intervals, and the control unit is configured to generate the negative voltage at each measurement timing. The driving of the application circuit is stopped and the driving of the positive voltage application circuit is alternately stopped.

  According to a third aspect of the present invention, the static eliminator according to the first or second aspect includes a determination unit that determines whether or not there is a discharge abnormality in the discharge electrode based on a change in a discharge state monitored by the discharge monitoring unit. .

  According to a fourth aspect of the present invention, in the static eliminator according to any one of the first to third aspects, the change in the discharge state of positive ions and the change in the discharge state of negative ions monitored by the discharge monitoring unit. And a voltage adjusting unit that adjusts an applied voltage of at least one of the negative voltage applying circuit and the positive voltage applying circuit so as to balance discharge between both ions.

<Invention of Claim 1>
According to this configuration, the negative voltage application circuit and the positive voltage application circuit are always driven to perform the static elimination operation for generating positive and negative ions from the pair of discharge electrodes, while the above measurement is performed at a predetermined measurement timing. Change the discharge state of the discharge electrode by driving the other application circuit based on the measurement signal output from the current measurement unit at this time (the voltage is applied by the driving application circuit during driving). Change in the discharge state of the discharge electrode). Therefore, it is only necessary to provide a common counter electrode for a pair of discharge electrodes, and the arrangement and wiring of the counter electrodes and the wiring can be simplified as compared with the conventional one in which a counter electrode is provided for each discharge electrode. Can do.

<Invention of Claim 2>
According to this configuration, the driving of the negative voltage application circuit for monitoring changes in the discharge state of positive ions and the driving stop of the positive voltage application circuit for monitoring changes in the discharge state of negative ions are performed. By performing alternately at the same time interval, it is possible to perform static elimination with balanced ions.

<Invention of Claim 3>
According to this configuration, for example, it is possible to detect a discharge abnormality in which the discharge amount of ions decreases due to dust or the like in the surrounding air adhering to the discharge electrode.

<Invention of Claim 4>
According to this configuration, the discharge balance state of positive ions and negative ions is recognized based on monitoring by the discharge monitoring unit, and this balance is achieved (for example, the discharge amount of positive ions and negative ions is the same amount). The applied voltage of the application circuit is adjusted.

An embodiment of the present invention will be described with reference to FIGS.
1. Overall configuration of the static eliminator The static eliminator of the present embodiment is of a direct current type and includes discharge needles 1 and 2 (an example of “a pair of discharge electrodes”) that generate positive and negative ions, respectively.

  The commercial AC power supply 3 is connected to the primary side of the transformer 5 via the first switch element 4 and to the primary side of the transformer 7 via the second switch element 6. A secondary side of the transformer 5 is connected to a cockcroft type voltage doubler rectifier circuit 10 (an example of a “negative voltage application circuit”) including a first capacitor 8 and a second capacitor 9. The discharge needle 1 is connected to the negative electrode side via the output terminal 14.

  The secondary side of the transformer 7 is connected to a cockcroft type voltage doubler rectifier circuit 13 (an example of a “positive voltage application circuit”) including a first capacitor 11 and a second capacitor 12. The discharge needle 2 is connected to the positive electrode side via the output terminal 15. The other output terminal (not shown) of each voltage doubler rectifier circuit 10, 13 is connected to the ground line GND.

  An N-channel power having a resistor 20 and a variable voltage source 21 between the output terminal 15 of one of the voltage doubler rectifier circuits 10 and 13 (in this embodiment, the voltage doubler rectifier circuit 13) and the ground line. A series circuit with a MOSFET (hereinafter referred to as “FET 22”) is provided, and a discharge circuit 24 including a resistor 23 connected in parallel to the FET 22 is provided. The variable voltage source 21 changes the gate voltage of the FET 22 to change its resistance value, thereby adjusting the charging current of the second capacitor 12 flowing in the discharge circuit 24. The FET 22 is operated in a non-saturated region.

2. Operation of Control Circuit Now, an electrode plate 30 (an example of a “counter electrode”) is provided at a position equidistant from both discharge needles 1 and 2, and a resistor 31 (an example of a “current measurement unit”) is connected thereto. The voltage generated in the resistor 31 according to the ion current (an example of the sampling voltage Vs “measurement signal”) is taken into the control circuit 40.

  The control circuit 40 gives control signals S1 and S2 to the first switch element 4 and the second switch element 6 to perform on / off control. Specifically, as shown in FIG. 2, the control circuit 40 turns off only one switch element of the first switch element 4 and the second switch element 6 for a first time interval T1 ((2) in FIG. 2 or Next, turn on both the first switch element 4 and the second switch element 6 for the second time interval T2 (an example of the “continuous execution period of static elimination operation”) (see (1) in FIG. 2). Then, the operation of turning off only the other switch element (see the period (2) or (3) in FIG. 2) is repeated. In short, the control circuit 40 alternately repeats the off operation of the first switch element 4 and the off operation of the second switch element 6 at each second time interval T2.

  In the period (1) in which both the first switch element 4 and the second switch element 6 are turned on, the double voltage rectifier circuits 10 and 13 are driven, and a high voltage is applied to both discharge needles 1 and 2 by corona discharge. Static elimination operation in which positive and negative ions are generated is executed. In the period (2) in which only the first switch element 4 is turned off, the voltage doubler rectifier circuit 10 that outputs the negative voltage is stopped, and only the voltage doubler rectifier circuit 13 that outputs the positive voltage is driven. Therefore, the sampling voltage Vs in the resistor 31 has a value corresponding to the current (positive ion current) flowing through the electrode plate 30 among the positive ions generated from the discharge needle 2. Therefore, it is possible to monitor a change in the discharge state (ion generation amount) of positive ions based on the sampling voltage Vs at this time.

  On the other hand, in the period (3) in which only the second switch element 6 is turned off, the voltage doubler rectifier circuit 13 that outputs the positive voltage is stopped and only the voltage doubler rectifier circuit 10 that outputs the negative voltage is driven. Therefore, the sampling voltage Vs in the resistor 31 has a value corresponding to the current (negative ion current) flowing through the electrode plate 30 among the negative ions generated from the discharge needle 1. Accordingly, it is possible to monitor the change in the discharge state (ion generation amount) of negative ions based on the sampling voltage Vs at this time.

  The first time interval T1 is shorter than the second time interval T2, and more specifically, the first time interval T1 is set to 10% or less with respect to the second time interval T2. If set in this way, the ion balance will not be destroyed so as to affect the charge removal performance of the charge removal apparatus. In the present embodiment, for example, the first time interval T1 is set to 30 ms, and the second time interval T2 is set to 300 ms.

  As described above, the static eliminator generates positive and negative ions in the period (1) to perform the static elimination operation of a not-shown charged body, and (2) drives only the voltage doubler rectifier circuit 13 in the period to obtain the sampling voltage Vs. Based on this, the change in the discharge state of positive ions is monitored, and during the period (3), only the voltage doubler rectifier circuit 10 is driven and the change in the discharge state of negative ions is monitored based on the sampling voltage Vs.

  Then, for example, the control circuit 40 compares the discharge amount of positive ions (ion generation amount) detected in each of the periods (2) and (3) with the discharge amount of negative ions (ion generation amount) as needed, If there is a difference between them, the voltage of the variable voltage source 21 is adjusted so as to cancel the difference. Specifically, for example, when the discharge amount of positive ions is larger than the discharge amount of negative ions, the control circuit 40 controls to raise the voltage of the variable voltage source 21 and raises the gate voltage of the FET 22 to thereby increase the voltage. Decrease the resistance value. Then, when the charging current to the second capacitor 12 flows to the discharge circuit 24, the charging voltage of the second capacitor 12 decreases, and the discharge amount of positive ions approaches the discharge amount of negative ions.

When the sampling voltage Vs becomes lower than the reference voltage Vref due to the positive discharge amount being smaller than the negative discharge amount, the control circuit 40 controls the FET 22 to reduce the voltage of the variable voltage source 21, thereby controlling the FET 22. The resistance value is increased by lowering the gate voltage. Then, the charging current of the second capacitor 12 flowing through the discharge circuit 24 is limited, so that the charging voltage of the second capacitor 12 increases, and the discharge amount of positive ions approaches the discharge amount of negative ions.
By doing in this way, the ion balance of the positive / negative ion produced | generated from the discharge needles 1 and 2 is maintained.

  Further, for example, when dust or the like in the surrounding air adheres to the discharge needles 1 or 2 or the tips of the discharge needles 1 or 2 are worn due to long-term use, the amount of discharge generated from the discharge needles 1 and 2 is reduced. It may be less than a predetermined level and affect the static elimination effect. Therefore, in the present embodiment, the control circuit 40 compares the sampling voltage Vs in the (2) period and (3) period with a predetermined threshold value, and the positive ion or negative voltage is so low that the sampling voltage Vs falls below the predetermined threshold value. When the discharge amount of at least one of the ions decreases, it is determined that a discharge abnormality has occurred, and an abnormality signal is output to the outside, for example. Moreover, the structure which lights the indicator lamp with which the static elimination apparatus was equipped may be sufficient. Furthermore, the structure which stops the drive of the fan (not shown) for spraying the positive / negative ion produced | generated with the discharge needles 1 and 2 to a charging body may be sufficient.

3. Advantages of the present embodiment As described above, according to the present embodiment, the static elimination operation that always drives both the voltage doubler rectifier circuits 10 and 13 to generate positive and negative ions from the pair of discharge needles 1 and 2 is performed. On the other hand, only one of the double voltage rectifier circuits 10 and 13 is driven at a predetermined measurement timing (periods (2) and (3)), and the discharge amount of positive ions or negative ions generated at this time To monitor. Therefore, it is only necessary to provide a common electrode plate 30 for the pair of discharge needles 1 and 2, and the arrangement and wiring of the counter electrode and the wiring are simplified compared to the conventional one in which a counter electrode is provided for each discharge electrode. Can be achieved.

  Further, the drive stop of the voltage doubler rectifier circuit 10 for monitoring the discharge amount of positive ions and the drive stop of the voltage doubler rectifier circuit 13 for monitoring the discharge amount of negative ions are alternately performed at the same time interval T1. In this way, it is possible to perform static elimination with an ion balance.

  Further, as shown in FIG. 2, the measurement timing of one ion (for example, positive ion) is located in the middle of the two measurement timings of the other ion (for example, negative ion) before and after that. That is, the measurement timing of one ion is set as far as possible from the measurement timing of the other ion. Thereby, due to the tracking delay of the voltage doubler rectifier circuits 10 and 13, for example, at the measurement timing of positive ions, the voltage doubler rectifier circuit 10 is not yet completely stopped, and the discharge amount of positive ions cannot be monitored accurately. Can be avoided.

  If the voltage doubler rectifier circuits 10 and 13 are alternately driven in the static elimination operation, the counter electrode can be made one. However, in this case, positive and negative ions are not generated simultaneously in the static elimination operation. There is a drawback that the charge removal effect is reduced. On the other hand, since the static elimination apparatus of this embodiment is the structure which drives the voltage doubler rectifier circuits 10 and 13 simultaneously and produces | generates positive / negative ion simultaneously, it can anticipate sufficient static elimination effect.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In the above embodiment, the voltage adjusting means is provided on the voltage doubler rectifier circuit 13 side, and when the ion balance of positive and negative ions is lost, the voltage adjusting means adjusts the output voltage of the voltage doubler rectifier circuit 13. However, the present invention is not limited to this, and voltage amphoteric means is provided in both voltage doubler rectifier circuits 10 and 13 so that each voltage adjusting means is individually set so that the discharge amount of each of positive ions and negative ions becomes a predetermined level. The structure to drive may be sufficient. Moreover, the structure which does not have a voltage adjustment means may be sufficient.

The circuit diagram which shows the electrical constitution of the static elimination apparatus which concerns on one Embodiment of this invention. Time chart for explaining the operation of the control circuit

Explanation of symbols

1, 2, ... Discharge needle (discharge electrode)
10 ... Voltage doubler rectifier circuit (negative voltage application circuit)
13 ... Voltage doubler rectifier circuit (positive voltage application circuit)
30 ... Electrode plate (counter electrode)
31 ... Resistance (current measuring part)
40... Control circuit (control unit, determination unit, discharge monitoring unit, timing generation unit)
T2 ... 2nd time interval (Execution period of static elimination operation, predetermined time interval)
Vs: Sampling voltage (measurement signal)
T1 ... 1st time interval (continuous execution time)

Claims (4)

A pair of discharge electrodes;
A negative voltage application circuit for generating negative ions by applying a negative voltage to one discharge electrode of the pair of discharge electrodes;
A positive voltage application circuit for generating positive ions by applying a positive voltage to the other discharge electrode;
A common counter electrode provided corresponding to the pair of discharge electrodes;
A current measurement unit that outputs a measurement signal corresponding to the current flowing through the counter electrode;
Usually, both the negative voltage application circuit and the positive voltage application circuit are driven to perform a direct current neutralization operation for generating positive and negative ions from the pair of discharge electrodes, while a predetermined measurement timing is A controller that selectively stops driving of the application circuit of either the negative voltage application circuit or the positive voltage application circuit in a period shorter than each continuous execution period of the static elimination operation when it arrives; ,
A discharge monitoring unit that monitors a change in a discharge state of the discharge electrode by the other application circuit based on the measurement signal output from the current measurement unit at the measurement timing. A timing generation unit that generates the measurement timing every predetermined time interval;
The static eliminator according to claim 1, wherein the controller alternately stops driving the negative voltage application circuit and stopping driving the positive voltage application circuit at each measurement timing. The static elimination apparatus of Claim 1 or Claim 2 provided with the judgment part which judges the presence or absence of the discharge abnormality of the said discharge electrode based on the change of the discharge state monitored by the said discharge monitoring part. The negative voltage application circuit and the positive voltage application circuit so as to balance the discharge between both ions based on the change in the discharge state of positive ions and the change in the discharge state of negative ions monitored by the discharge monitoring unit. The static elimination apparatus in any one of Claims 1-3 provided with the voltage adjustment part which adjusts at least any one applied voltage among these.

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