JP5686655B2 - Static eliminator - Google Patents

Description

  The present invention relates to a static eliminator that removes static electricity.

  Conventionally, for example, a configuration described in Patent Document 1 is known as a static eliminator that alternately generates positive ions and negative ions. The static eliminator includes first and second high voltage generation circuits connected to a DC power source via first and second switches, respectively. The first high voltage generation circuit boosts the DC voltage of the DC power source to generate a positive high voltage, and the second high voltage generation circuit also generates a negative high voltage. Two equivalent resistors are connected in series between the output terminals of the first and second high voltage generation circuits, and a discharge needle is connected to the connection point of these resistors. Through the opening / closing control of the first and second switches by the controller of the static eliminator, positive and negative pulsed high voltages are alternately applied to the discharge needle. That is, by applying an AC pulse voltage with positive and negative polarities periodically reversed to the discharge needle, positive and negative ions are generated alternately by corona discharge around the tip of the discharge needle.

  In the static eliminator, the higher the accuracy of the positive ion and negative ion balance (hereinafter referred to as “ion balance”) generated, the closer to 0 V, the more accurate the static elimination can be performed. When the ion balance is lost, stable charge removal becomes difficult, for example, reverse charge that reversely charges the charge removal object occurs or complete charge removal cannot be performed. In this regard, in Patent Document 1, ion balance is adjusted by adjusting positive and negative voltage application times, that is, pulse widths of positive and negative voltages, through control of the opening and closing times of the first and second switches. It is possible to adjust. At this time, the ratio of the opening and closing times of the first and second switches is adjusted so that the sum of the positive duty ratio D1 and the negative duty ratio D2 is 100%. Here, the positive duty ratio D1 refers to the ratio of the positive pulse width to one cycle of the AC pulse voltage. The negative duty ratio D2 refers to the ratio of the negative pulse width to one cycle of the AC pulse voltage.

JP 2000-58290 A

  As shown in FIG. 4A, when the positive pulse width (= time T1) and the negative pulse width (= time T2) are equal, that is, the positive duty ratio D1 and the negative duty ratio D2 are respectively Even if it is 50%, it is conceivable that a difference occurs in the generation amount of positive ions and negative ions. In this case, since the ion balance is deteriorated, it is necessary to adjust the ion balance.

  Here, as shown in FIG. 5A, it is assumed that the ion balance is −10 V when the positive duty ratio D1 and the negative duty ratio D2 are 50%. At this time, in order to achieve ion balance, it is necessary to increase positive ions. For example, when the frequency of the AC pulse voltage applied to the discharge needle is 100 Hz and the interrupt period of the control device is 20 μs, the positive duty ratio D1 is set to one step (here, as indicated by an arrow in FIG. 4B). In this case, the negative duty ratio D2 is decreased by one step. The adjustment results of these duty ratios D1 and D2 are expressed by the following equation (X).

D1: D2 = 50.20%: 49.80% (X)
As a result of the adjustment, the application time of the positive pulse voltage increases, so that the amount of positive ions generated increases. On the contrary, the amount of negative ions to be generated decreases as the application time of the negative pulse voltage decreases. As a result, the proportion of positive ions in the total generated ions increases at a stretch.

  As shown in FIG. 5B, when the ion balance after the adjustment was actually measured using a product model, the ion balance was about + 10V. That is, since the ion balance before adjustment is −10 V while the ion balance after adjustment is +10 V, it is understood that the minimum adjustment value (resolution) of the ion balance is about 20 V.

  As described above, the ion balance is preferably closer to 0V. However, when the minimum adjustment value is 20 V, it may be difficult to adjust the ion balance to the required level. For example, when the ion balance is approximated to 0 V, it is necessary to increase negative ions in the opposite direction. In this case, the positive duty ratio D1 is decreased by one step, and the negative duty ratio D2 is increased by one step. Then, the positive and negative duty ratios D1 and D2 eventually have the original relationship represented by (X). The ion balance changes from + 10V to a value approximating the original -10V.

  As described above, when adjusting the ion balance, the method of adjusting the positive and negative duty ratios D1 and D2 at the same time is concerned that the ion balance may fluctuate greatly as a whole. Further, when it is not possible to cope with a situation where fine adjustment of the ion balance is required, there is a possibility that the static eliminator becomes difficult to handle for the user.

  Note that the increase / decrease value for one step of the positive / negative duty ratios D1, D2, that is, the minimum adjustment value of the ion balance, varies depending on the frequency of the AC pulse voltage. However, problems similar to those described above can occur to varying degrees.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a static eliminator capable of improving the accuracy of ion balance adjustment.

According to the first aspect of the present invention, an AC pulse voltage whose polarity is reversed at a specific period is applied to a single discharge needle, and positive and negative ions in amounts corresponding to the positive and negative pulse widths of the AC pulse voltage are applied. When the positive / negative duty ratio , which is the ratio of the positive / negative pulse width to one cycle of the AC pulse voltage, is adjusted in a plurality of stages, the positive / negative duty ratio is increased or decreased by one side. The gist of the invention is that it comprises a control circuit for controlling the amount of ions generated.

  According to the present invention, the minimum adjustment value (resolution) of the ion balance is small as compared with the case where the positive and negative duty ratios are adjusted simultaneously so that the sum of these is 100%. This is because the amount of change in the generation amount of positive and negative ions is reduced by increasing or decreasing the positive and negative duty ratios one by one. Therefore, the ion balance adjustment accuracy can be improved.

  In addition, as described in claim 2, it is preferable that the positive / negative duty ratio is increased or decreased by a minimum unit that can be adjusted. In this way, the generation amount of positive and negative ions can be controlled more finely.

  Moreover, as a static elimination apparatus, the structure described in Claim 3 is employ | adopted, for example. That is, the static eliminator boosts the power supply voltage and applies a positive high voltage to the discharge needle, and also applies a negative high voltage to the discharge needle. And a second switch for opening and closing the second power supply path. The control circuit generates the AC pulse voltage by alternately turning on and off the first and second switches. The control circuit controls on / off times of the first and second switches according to the positive / negative duty ratio.

  Further, as described in claim 4, the static eliminator may be provided with an input device for inputting a command to increase or decrease the positive / negative duty ratio. In this case, the control circuit increases or decreases the positive / negative duty ratio based on a command input through the input device. According to this configuration, the positive / negative ion balance can be appropriately adjusted via the input device.

  Furthermore, as described in claim 5, it is also possible to provide the static eliminator with a detection circuit that detects an ionic current generated between the discharge needle and the ground according to the amount of positive and negative ions. The control circuit increases or decreases the positive / negative duty ratio based on the detection result of the detection circuit. In other words, according to this configuration, the positive / negative ion balance is automatically adjusted according to the actual ion balance detected from time to time. For this reason, the usability of the static eliminator is improved.

  According to the present invention, the accuracy of ion balance adjustment can be improved by alternately increasing or decreasing the positive / negative duty ratio.

The circuit diagram of a static elimination apparatus. (A)-(d) is a wave form diagram of the alternating current pulse voltage applied to a discharge needle. (A)-(d) is a wave form diagram which shows the change of ion balance. (A), (b) is the wave form diagram of the conventional alternating current pulse voltage. (A), (b) is a wave form diagram which shows the change of the conventional ion balance.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the static eliminator 11 includes first and second high voltage generation circuits 13 and 14 connected between a plus terminal and a minus terminal of a DC power supply 12, respectively. The first high voltage generation circuit 13 generates a positive DC high voltage by boosting the DC voltage (power supply voltage) of the DC power supply 12. The second high voltage generation circuit 14 generates a negative DC high voltage by boosting the DC voltage of the DC power supply 12.

  A first switch 15 is provided between the plus terminal of the DC power supply 12 and the first high voltage generation circuit 13, and a second switch is provided between the plus terminal of the DC power supply 12 and the second high voltage generation circuit 14. A switch 16 is provided. As the first and second switches 15 and 16, electronic switching elements such as field effect transistors (FETs) are employed.

A discharge needle 18 is connected to a connection point 17 between the output terminal of the first high voltage generation circuit 13 and the output terminal of the second high voltage generation circuit 14.
The control circuit 19 of the static eliminator 11 controls the generation of positive ions and negative ions through on / off control of the first and second switches 15 and 16.

  When the first switch 15 is in the on state and the second switch 16 is in the off state, a positive direct current high voltage generated in the first high voltage generation circuit 13 is applied to the discharge needle 18. Is done. As a result, positive ions are generated around the tip of the discharge needle 18 by corona discharge.

  When the first switch 15 is in the off state and the second switch 16 is in the on state, a negative direct current high voltage generated in the second high voltage generation circuit 14 is applied to the discharge needle 18. Is done. As a result, negative ions are generated by corona discharge around the tip of the discharge needle 18.

  As shown in FIG. 2A, after the control circuit 19 applies the positive pulse voltage to the discharge needle 18 by turning on the first switch 15 and turning off the second switch 16 for the time T1. For the time T2, the first switch 15 is turned off and the second switch 16 is turned on to apply a negative pulse voltage to the discharge needle 18. After that, the control circuit 19 turns on the first switch 15 again and turns off the second switch 16 to apply a positive pulse voltage to the discharge needle 18. Thereafter, similarly to the above, the control circuit 19 alternately turns on and off the first and second switches 15 and 16 to discharge the AC pulse voltage whose polarity is reversed in the cycle T (T = T1 + T2). Apply to needle 18. As a result, positive and negative ions are generated alternately by corona discharge around the tip of the discharge needle 18. The generated ions are supplied to the charge removal target.

  The frequency of the AC pulse voltage applied to the discharge needle 18 is set according to the distance between the discharge needle 18 and the charge removal target. The control circuit 19 controls on / off of the first and second switches 15 and 16 in accordance with the determined frequency. The frequency of the AC pulse voltage is determined by the number of repetitions of the period T per unit time (for example, 1 second). An AC pulse voltage having a predetermined frequency is applied to the discharge needle 18.

  An input device 20 is connected to the control circuit 19. The input device 20 has, for example, two rotary switches. These rotary switches are provided corresponding to the positive polarity and the negative polarity, respectively. Through the operation of the input device 20 (more precisely, two rotary switches), the balance between positive ions and negative ions, that is, the ion balance can be adjusted. Specifically, by operating the input device 20, the values of the positive duty ratio D1 and the negative duty ratio D2 in one cycle of the AC pulse voltage can be individually adjusted for each determined minimum unit. Here, the positive duty ratio D1 refers to the ratio of the positive pulse width (= time T1) to one cycle (= T) of the AC pulse voltage applied to the discharge needle 18. The negative duty ratio D2 refers to the ratio of the negative pulse width (= time T2) to one cycle of the AC pulse voltage applied to the discharge needle 18. The control circuit 19 increases or decreases the positive and negative duty ratios D1 and D2 by every minimum unit that can be adjusted based on a command to increase or decrease the positive and negative duty ratios D1 and D2 generated in the input device 20.

  When the positive / negative duty ratios D1 and D2 are changed, the control circuit 19 turns on and off the first and second switches 15 and 16 in one cycle of the AC pulse voltage based on the changed positive and negative duty ratios D1 and D2. The time, that is, the pulse width of the positive and negative voltages is controlled. Since the amount of positive and negative ions generated is determined according to the pulse width of the positive or negative voltage applied to the discharge needle 18, positive and negative duty ratios D1 and D1 via the input device 20 are determined. It becomes possible to adjust the ion balance through the adjustment of D2.

  A charge monitor 21 is attached to the static eliminator 11. The charge monitor 21 detects the charge amount of the charge removal target. The charge monitor 21 displays the detection result of the charge amount through an indicator (not shown). Based on the displayed charge amount, it is possible to recognize that the ion balance is inclined to the positive polarity side or the negative polarity side, and to adjust the positive / negative duty ratios D1 and D2.

  Further, the static elimination device 11 includes an annular counter electrode 22. The counter electrode 22 is provided near the tip of the discharge needle 18. The counter electrode 22 is connected to the ground 24 through a resistor 23. A control circuit 19 is connected to a connection point 25 between the counter electrode 22 and the resistor 23 via a detection circuit 26. The detection circuit 26 detects an ionic current flowing to the ground 24 via the counter electrode 22. The ionic current is a current generated between the discharge needle 18 and the ground (here, the ground 24) according to the amount of positive and negative ions produced. The control circuit 19 detects the ion balance (voltage value) based on the detection result of the detection circuit 26. The control circuit 19 displays the ion balance detection result through a display device (not shown). It is also possible to adjust the positive and negative duty ratios D1 and D2 through the display device while confirming the ion balance at that time.

<Ion balance adjustment method>
Next, a method for adjusting the ion balance will be described. In this example, the ion balance is adjusted by alternately increasing and decreasing the positive duty ratio D1 and the negative duty ratio D2 one step at a time.

  Here, as shown in FIG. 2A, when the positive and negative duty ratios D1 and D2 are 50%, the ion balance is −30 V on the negative polarity side as shown in FIG. Suppose that it is only tilted. Further, the frequency of the AC pulse voltage applied to the discharge needle 18 is 100 Hz, and the interrupt period of the control circuit 19 is 20 μs. At this time, when the positive and negative duty ratios D1 and D2 are increased or decreased by one step through the operation of the input device 20, the change amount of the positive and negative duty ratios D1 and D2, that is, the minimum unit for adjusting the positive and negative duty ratios is 0. .2%. The required level of ion balance is ± 5V.

  Now, since the ion balance is inclined to the negative polarity here, only the negative duty ratio D2 is decreased by one step as shown in FIG. At this time, the adjustment result of the positive and negative duty ratios D1 and D2 is expressed by the following equation (A).

  When the sum of the positive and negative duty ratios D1 and D2 is less than 100%, that is, when the sum of the positive and negative pulse widths is less than the period (T> T1 + T2), the control circuit 19 calculates the total value of the positive and negative pulse widths. Both the first and second switches 15 and 16 are maintained in the OFF state for the time obtained by subtracting from the period T.

D1: D2 = 50.00: 49.80 (A)
The on-time of the second switch 16 in the period T is shortened by the amount by which the negative duty ratio D2 is decreased. For this reason, the quantity of the negative polarity ion produced | generated reduces. Since the positive duty ratio D1 is the same as the value before the adjustment, the proportion of negative ions in the total generated ions decreases. As a result, as shown in FIG. 3B, the ion balance increases by −10 V from −30 V before the adjustment to −20 V. At this stage, since the ion balance is still inclined to the negative polarity, the ion balance is further changed to the positive polarity side.

  This time, the negative duty ratio D2 is not decreased through the operation of the input device 20, but only the positive duty ratio D1 is increased by one step as shown in FIG. In this case, the adjustment result of the positive and negative duty ratios D1 and D2 is expressed by the following equation (B).

D1: D2 = 50.20: 49.80 (B)
The on-time of the first switch 15 in the period T is increased by the increase in the positive duty ratio D1. For this reason, the quantity of the positive ion produced | generated increases. Accordingly, the proportion of positive ions in the total generated ions increases. As a result, as shown in FIG. 3C, the ion balance after the adjustment increases by −10 V from −20 V before the adjustment to −10 V. Even at this stage, since the ion balance is greatly inclined toward the negative polarity, the ion balance is further changed to the positive polarity side.

  This time, instead of increasing the positive duty ratio D1, through the operation of the input device 20, only the negative duty ratio D2 is decreased by one step as shown in FIG. In this case, the adjustment result of the positive / negative duty ratios D1 and D2 is expressed by the following equation (C).

D1: D2 = 50.20: 49.60 (C)
The on-time of the second switch 16 in the period T is further shortened by the amount by which the negative duty ratio D2 is decreased. For this reason, the quantity of the negative polarity ion produced | generated reduces. Accordingly, the proportion of negative ions in the total generated ions decreases. As a result, as shown in FIG. 3D, the ion balance after the adjustment is increased by -10V from -10V before the adjustment to 0V. That is, the ion balance is a value within the required range of ± 5V.

This completes the ion balance adjustment work.
Even when the ion balance is greatly inclined toward the positive polarity side, the ion balance is adjusted in units of 10 V by alternately increasing / decreasing the positive / negative duty ratios D1 and D2 step by step, as described above. Can do.

  Thus, by increasing or decreasing the positive and negative duty ratios D1 and D2 alternately one step at a time, the minimum adjustment value (resolution) of the ion balance becomes about 10V. The minimum adjustment value is a value that is 1/2 of the positive / negative duty ratios D1 and D2 as compared to about 20 V, which is the minimum adjustment value when the total of these is adjusted to be 100% at the same time.

  Further, the increase / decrease value for one stage of the positive / negative duty ratios D1 and D2, that is, the minimum adjustment value of the ion balance differs depending on the frequency of the AC pulse voltage. However, as compared with the case where the positive and negative duty ratios D1 and D2 are adjusted at the same time so that the sum of them becomes 100%, the frequency of the AC pulse voltage described above is 100 Hz in that the minimum adjustment value is ½. This is the same as the case. For example, when the frequency of the AC pulse voltage is 10 Hz, the minimum adjustment value is about 1 V according to the conventional adjustment method, whereas it is 0.5 V according to the adjustment method of this example. When the frequency of the AC pulse voltage is 50 Hz, the minimum adjustment value is about 8V according to the conventional adjustment method, whereas it is 4V according to the adjustment method of this example.

<Effect of Embodiment>
Therefore, according to the present embodiment, the following effects can be obtained.
(1) When adjusting the ion balance, the positive and negative duty ratios D1 and D2 are alternately increased or decreased by one step. For this reason, the minimum adjustment value (resolution) of the ion balance is ½ compared to the case where the positive and negative duty ratios D1 and D2 are adjusted simultaneously so that the total of the positive and negative duty ratios D1 and D2 is 100%. . Therefore, the ion balance adjustment accuracy can be improved. Usability of the static eliminator 11 is also improved. If the deviation of the ion balance is slight, it may be assumed that the adjustment of the ion balance is completed by increasing or decreasing only one of the positive and negative duty ratios D1 and D2 by one step. The When the positive and negative duty ratios D1 and D2 are adjusted in a plurality of stages, it is preferable to alternately increase and decrease the positive and negative duty ratios D1 and D2 one by one as in this example.

  (2) When adjusting the ion balance, the positive and negative duty ratios D1 and D2 are increased or decreased by a predetermined minimum unit (in this example, 0.2%). For this reason, it becomes possible to control the generation amount of positive and negative ions more finely.

  (3) The input device 20 is provided to which a command to increase or decrease the positive / negative duty ratio is input. For this reason, the positive / negative ion balance can be appropriately adjusted via the input device 20.

<Other embodiments>
The embodiment described above may be modified as follows.
In this example, the input device 20 may be provided integrally with the static eliminator 11 or may be detachable.

  In this example, the ion balance is adjusted by adjusting the positive and negative duty ratios D1 and D2 through the operation of the input device 20, but the following may be used. That is, the ion balance is detected based on the detection result of the detection circuit 26, and the positive and negative duty ratios D1, D2 are automatically adjusted based on the detection result. Also in this case, it is preferable to adjust the positive and negative duty ratios D1 and D2 alternately one step at a time. According to this configuration, the positive / negative ion balance is automatically adjusted according to the actual ion balance detected from time to time. For this reason, the usability of the static elimination apparatus 11 improves. Further, when the static eliminator 11 is provided with an ion balance automatic adjustment function, the input device 20 can be omitted.

  In this example, when adjusting the ion balance, the positive and negative duty ratios D1 and D2 are alternately increased or decreased by one step, that is, by the minimum unit that can be adjusted. . For example, when the frequency of the AC pulse voltage is 10 Hz or 50 Hz, the positive and negative duty ratios D1 and D2 may be increased or decreased by a plurality of stages, that is, by a plurality of units.

<Other technical ideas>
Next, the technical idea that can be grasped from the above embodiment will be added below.
(A) A first switch that opens and closes a first power supply path that boosts the power supply voltage and applies a positive high voltage to the discharge needle, and a second switch that similarly applies a negative high voltage to the discharge needle. A second switch that opens and closes a power supply path; and a control circuit that controls on / off of the first and second switches, wherein the control circuit alternately turns on and off the first and second switches. In the static eliminator that alternately generates positive and negative ions in an amount corresponding to the positive and negative pulse width of the AC pulse voltage by applying an AC pulse voltage whose polarity is reversed at a specific cycle to the discharge needle. The control circuit is a static eliminator that controls the amount of positive and negative ions generated by alternately increasing and decreasing a positive and negative duty ratio, which is a ratio of positive and negative pulse widths to one cycle of the AC pulse voltage. According to this method, the same effect as that of the first aspect of the invention can be obtained.

  (B) Static elimination that alternately generates positive and negative ions in an amount corresponding to the positive and negative pulse widths of the AC pulse voltage by applying an AC pulse voltage whose polarity is reversed at a specific cycle to a single discharge needle. In the ion balance adjusting method in the apparatus, an ion balance adjusting method for adjusting positive and negative ion generation amounts by alternately increasing and decreasing a positive and negative duty ratio which is a ratio of positive and negative pulse widths to one cycle of the AC pulse voltage. According to this method, the same effect as that of the first aspect of the invention can be obtained.

  DESCRIPTION OF SYMBOLS 11 ... Static elimination apparatus, 15 ... 1st switch, 16 ... 2nd switch, 18 ... Discharge needle | hook, 19 ... Control circuit, 20 ... Input device, 26 ... Detection circuit.

Claims (5)

In a static eliminator that applies an alternating pulse voltage whose polarity is reversed at a specific period to a single discharge needle and alternately generates positive and negative ions in an amount corresponding to the positive and negative pulse width of the alternating pulse voltage,
When the positive / negative duty ratio , which is the ratio of the positive / negative pulse width to one cycle of the AC pulse voltage, is adjusted in a plurality of stages, the positive / negative duty ratio is increased / decreased one by one to control the generation amount of positive / negative ions. A static eliminator comprising a control circuit. The static eliminator according to claim 1,
The control circuit is a static eliminator that controls the amount of positive and negative ions generated by increasing or decreasing the positive / negative duty ratio for each minimum unit that can be adjusted. In the static elimination apparatus of Claim 1 or Claim 2,
A first switch that opens and closes a first power supply path that boosts the power supply voltage and applies a positive high voltage to the discharge needle, and a second power supply path that similarly applies a negative high voltage to the discharge needle. A second switch that opens and closes,
The control circuit generates the AC pulse voltage by alternately turning on and off the first and second switches, and controls on and off times of the first and second switches according to the positive and negative duty ratios. Static neutralizer. In the static elimination apparatus as described in any one of Claims 1-3,
An input device for inputting a command to increase or decrease the positive / negative duty ratio;
The control circuit is a static eliminator that increases or decreases the positive / negative duty ratio based on the command input through the input device. In the static elimination apparatus as described in any one of Claims 1-4,
A detection circuit that detects an ionic current generated between the discharge needle and the ground according to the amount of the positive and negative ions;
The control circuit is a static eliminator that increases or decreases the positive / negative duty ratio based on a detection result of the detection circuit.

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