JP4465232B2 - Static elimination control method of static eliminator - Google Patents

Description

  The present invention relates to a pulse AC type static eliminator, and more particularly, to a static elimination control method for a static eliminator that alternately discharges positive ions and negative ions by alternately applying pulse voltages having different polarities to the same discharge needle. .

  Static cleaners using corona discharge are widely used as non-contact type static elimination methods for cleaning in clean rooms, preventing static charge of suspended particles, and eliminating static charges on charged workpieces.

  With respect to this type of static eliminator, Patent Document 1 discloses a pulse that alternately applies pulse voltages for ion generation with different polarities to the same discharge needle at predetermined intervals, and intermittently releases positive ions and negative ions alternately. A static elimination control method for an AC static eliminator has been proposed. Also, in this Patent Document 1, immediately after applying this ion generating pulse voltage to the discharge needle, a needle voltage neutralizing pulse voltage for almost neutralizing the potential remaining on the discharge needle is applied to the discharge needle. Propose that.

According to the control method disclosed in Patent Document 1, an interval is provided in the middle of applying the positive ion generation pulse voltage and the next negative ion generation voltage to the discharge needle. Since the amount of work can be reduced, there are advantages that the frequency of maintenance of the discharge needle, wear and contamination of the discharge needle can be reduced, and ion balance can be maintained over a long period of time.
JP 2003-86393 A

  FIG. 1 is a conceptual diagram of a static elimination control method disclosed in Patent Document 1 relating to a pulse AC type static eliminator. As can be understood from the figure, according to the control method of Patent Document 1 in which a pulse voltage for generating ions of opposite polarity is alternately applied to the discharge needle 100 at intervals of t, the static eliminator intermittently positive ions And negative ions are emitted alternately. For example, with respect to the workpiece W charged to the plus side, the plus-side released ions do not contribute to the charge removal of the workpiece W. There is a problem that it takes time to arrive, and the time required for static elimination increases.

  The present invention has been made in consideration of the above problems, and its purpose is to reduce the frequency of discharge needle maintenance, discharge needle wear and contamination, and maintain the ion balance over a long period of time. It is an object of the present invention to provide a static elimination control method for a static eliminator that can shorten the period.

According to the present invention, the above technical problem is
A static elimination control method for a static eliminator that alternately discharges positive ions and negative ions by alternately applying pulse voltages for ion generation with different polarities to the same discharge needle,
A step of repeatedly performing an ion emission cycle in which a plurality of pulse voltages for generating ions having different polarities are alternately applied to the discharge needle with an interval period;
At the beginning of the interval period, a needle voltage neutralizing pulse voltage for neutralizing the residual potential of the discharge needle having a polarity opposite to that of the ion generating pulse voltage immediately before the interval period is applied to the discharge needle. A process,
In each ion emission cycle, the ion generation pulse voltage is applied to the discharge needle an odd number of times, and the last ion generation pulse voltage of the ion emission cycle immediately before the interval period and immediately after the interval period are applied. This is achieved by providing a static elimination control method for a static eliminator characterized in that the pulse voltage for generating ions at the end of the ion emission cycle has a reverse polarity.

According to the static elimination control method of the present invention, as shown in the conceptual diagram of FIG. 2, an ion release cycle in which a plurality of ion generation pulse voltages having different polarities are alternately applied to the discharge needle 100 is repeated with an interval period t. As a result, ion groups G ₁ , G ₂ ,... Containing positive ions and negative ions are intermittently released. In addition, since both positive and negative ions exist in each of the emitted ion groups G ₁ , G ₂ ,..., Regardless of whether the workpiece W is charged on the positive side or the negative side, The work W can be neutralized by negative ions or positive ions contained in each of the emitted ion groups G ₁ , G ₂ ,. That is, referring to FIG. 2, when one emitted ion group G ₁ arrives at the work W, the emitted ion group G ₁ contains ions having a polarity opposite to the charged polarity of the work W (for example, the work W has When it is positively charged, it always contains negative ions that contribute to static elimination), so that the static elimination time can be shortened. The ion generation pulse voltage is applied to a discharge needle to generate corona discharge to generate ions. The pulse width and absolute voltage value of the ion generation pulse voltage are determined by the static eliminator manufacturer. Although it may be set in advance, it may be arbitrarily set by the user.

  In the static elimination control method of the present invention, the number of pulses of the ion generation pulse voltage included in each ion emission cycle is an odd number (for example, 3, 5, 7, etc.) excluding “1”. The ion generation pulse voltage immediately before each interval period and the ion generation pulse voltage immediately before the next interval period have opposite polarities.

This point will be described with reference to FIG. 2. If the released ion immediately before the interval period t ₁ (the last released ion of the ion group G ₁ ) is a negative ion, it is released immediately before the next interval period t _2. ions (the last release of the ionic group G ₂₎ is such that the positive ions, the polarity of the ion generating pulse voltage on each ion emission cycle is controlled.

  The ion balance in the interval period depends on the polarity of the emitted ions immediately before the interval period t. Therefore, as described above, by alternating the polarity of the emitted ions immediately before each interval period t, it is possible to prevent the bias of the ion balance during the interval period and maintain a good ion balance.

In other words, all of the interval period t _1, t _2, upon application of an ion generating pulse voltage immediately before the ... for example a positive voltage to the discharge needle 100, all of the interval period t _1, t _2, · · However, according to the present invention, since the polarity of the emitted ions immediately before each interval period is alternated, an ion release cycle that is repeatedly performed is performed. In the process of execution, it is possible to suppress the bias of ion balance in the interval period.

In the ionization method of the present invention, as described above, positive and negative ion generation pulse voltages are alternately applied to the discharge needle in each ion emission cycle. The number of pulses is an odd number except for “1”. From another point of view, this can be rephrased that the polarity of the pulse voltage for generating ions at the beginning and the end of each ion emission cycle is the same. it can. For example, initial release ions released ion group G ₁ in FIG. 2 is a negative ion, the last release ions of the release ionic group G ₁ is also negative ions.

  Further, according to the static elimination control method of the present invention, the pulse voltage for neutralizing the needle potential for neutralizing the residual potential of the discharge needle is applied to the discharge needle at the beginning of each interval period t. The potential remaining on the discharge needle can be eliminated at an early stage, thereby preventing contamination of the discharge needle due to this residual potential remaining on the discharge needle forever.

  The interval period t is typically fixed. The time length of the fixed interval period t may be set in advance by the static eliminator maker, or may be arbitrarily set by the user. When the time length of the interval period t is set to be relatively large, the static elimination speed is reduced, but the work amount per unit time of the discharge needle is reduced, so that the maintenance period of the discharge needle can be extended. Conversely, when the time length of the interval period t is set small, the static elimination speed can be made relatively fast, but on the other hand, the discharge needle maintenance period is shortened.

The static elimination control method according to the present invention in which the ion release cycle is repeatedly performed with an interval period t is to efficiently stop the discharge needle. In order to make the rest of the discharge needle rational, the interval period t may be variably controlled according to the charging state of the workpiece. More specifically, as an example, the static elimination state of the workpiece by the ion emission cycle executed in the previous stage of each interval period t, that is, the charged state of the workpiece is detected, and the charged (static elimination) state is a predetermined charging (static elimination) state When it is determined that the state is closer to the neutralized state than the reference value, the interval period t immediately after that is set to be longer than the predetermined interval period t ₀ , and conversely, the workpiece is charged (static charge). when the state is determined to be in the state away from the pre-defined charging (neutralization) neutralized state than the reference value of the state, set to be shorter than the interval period t ₀ in advance define the immediately following interval period t That's fine.

  Instead of allowing the user to arbitrarily set the t time length of the interval period, a plurality of operation modes having different time lengths of the interval period may be prepared so that the user can select an appropriate operation mode. This operation mode may include an operation mode without an interval. The time length of the interval period t in each operation mode may be set in advance by the manufacturer, but may be arbitrarily set by the user. A user who wants to shorten the static elimination time will select an operation mode with a relatively short interval period, and a user who wants to extend the maintenance period will select an operation mode with a relatively long interval period.

  In order to keep the ion balance good, the ion release amount in the latter half of each ion release cycle may be suppressed in order to reduce the bias of the ion balance in the interval period t. As described above, the ion balance in the interval period t greatly depends on the last released ions in each ion release cycle. For example, at least the last ion generation pulse voltage in each ion release cycle is relatively small, A good ion balance may be maintained in the interval period t by reducing the amount of ions released at the end of the ion release cycle. As a specific method for variably controlling the pulse voltage for ion generation, control for changing the pulse width and / or absolute voltage value of the pulse voltage for ion generation can be mentioned.

  In order to actively maintain a good ion balance, it is preferable to perform feedback control of the ion balance. That is, when the ion balance is detected and the detected ion balance is biased to the plus or minus side, in order to correct the bias of the ion balance, for example, a positive-side ion generation pulse voltage included in the ion emission cycle However, the bias of the ion balance can be corrected by performing control so as to be relatively higher than the negative-side ion generation pulse voltage. In this feedback control, the polarity of negative or positive ion generation pulse voltage on one side may be fixed, and only the ion generation pulse voltage of the other polarity may be variably controlled. According to this, there exists an advantage that control of the high voltage generation part for producing | generating the pulse voltage for ion generation contained in a static elimination apparatus becomes easy.

  In order to improve the convenience of the user of the static eliminator, as the operation mode, the above-described interval operation mode in which the interval period t is provided, and the ion generation pulse voltage having different polarities alternately with the discharge needle are alternately alternated. However, when performing ion balance feedback control, it is preferable to control based on a different control formula for each operation mode because the control system becomes complicated. Absent. As one method for dealing with this, ion balance detection is performed in synchronization with the timing of applying the second and subsequent ion generation pulse voltages excluding the first ion generation pulse voltage in each ion emission cycle in the interval operation mode. It is good. Since the second and subsequent ion generation pulse voltages have the same transient characteristics of the voltage rise at the tip of the discharge needle as in the operation mode with no interval period, the ion balance is applied during the second and subsequent ion emission cycles of the ion emission cycle. By detecting this, feedback control of ion balance can be performed based on a common control equation in both operation modes.

  When the ion generation pulse voltage is variably controlled as described above, the potential remaining on the discharge needle may change. Therefore, if the pulse width and absolute voltage value of the needle neutralizing voltage are fixed, it takes time to neutralize the residual potential with the change of the residual potential of the discharge needle, or it cannot be neutralized. there is a possibility.

  In order to cope with this, it is preferable to variably control the pulse voltage for neutralizing the needle potential so that the residual potential of the discharge needle quickly becomes zero V (volt) at the beginning of the interval period. As described above, the potential remaining on the discharge needle during the interval period depends on the last ion generation pulse voltage of each ion emission cycle. Therefore, the residual potential of the discharge needle is effectively neutralized by controlling the needle potential neutralization pulse voltage so that the needle neutralization pulse voltage corresponds to the ion generation pulse voltage immediately before the interval period. be able to.

  As a specific method for variably controlling the needle neutralizing pulse voltage, there is a control for changing the pulse width and / or the voltage absolute value of the needle neutralizing voltage. For example, when the pulse width of the pulse voltage for ion generation at the end of each ion emission cycle is relatively small, the pulse width of the voltage for needle neutralization is controlled to be relatively small. When the pulse width of the last ion generation pulse voltage is made relatively large, neutralization of the residual potential of the discharge needle is optimized by controlling the pulse width of the needle neutralization voltage to be relatively large. Can do.

  Another example of variable control of the needle neutralizing pulse voltage will be described next. In the method of the present invention in which a plurality of ion generation pulse voltages are alternately applied to the discharge needle in each ion emission cycle, the frequency of ion emission in each ion emission cycle can be defined. For example, when the ion generation pulse voltage is changed for feedback control of the ion balance, the ion emission frequency changes accordingly, so the needle neutralization pulse voltage is variably controlled according to this frequency. By doing so, neutralization of the residual potential of the discharge needle can be optimized.

  Next, the best mode for carrying out the present invention will be described with reference to FIGS.

  FIG. 3 shows a pulse AC type static eliminator 1, which generates ion generation pulse voltages and needle neutralization pulse voltages having different polarities in positive and negative high voltage generation circuits 2 and 3. By alternately supplying different pulse voltages for generating ions to the same discharge needle 4, positive ions and negative ions are alternately released.

  Both the positive and negative high voltage generation circuits 2 and 3 include a self-excited oscillation circuit 7 connected to the primary coil of the transformers 5 and 6 and a booster circuit 8 connected to the secondary coil, such as a double rectifier circuit. Including. A protective resistor 9 is provided between the high voltage generation circuits 2 and 3 and the discharge needle 4.

A ground (GND) plate 10 is provided near or around the discharge needle 4, and the GND plate 10 is connected to a work side ground, that is, a frame ground FG through a conductor 11. Two resistors R ₁ and R ₂ are provided in series. Specifically, the first resistor R1 is provided on the GND plate 10 side, a second resistor _{R 2} is provided on the frame ground FG side. Then, this first resistor R1 and between the second resistor R _2, and the ground-side end of the secondary coil of the positive and negative of the transformer 5 and 6 are connected by a conductor 12.

The current I ₁ between the discharge needle 4 and the GND plate 10 can be indirectly detected by the potential difference V ₁ of the first resistor R ₁ . The difference in the amount of work side of the frame ground FG to reach the positive and negative ions, indirectly detected by the potential difference V ₂ of the current I _2, that the second resistor R ₂ through the second resistor R ₂ be able to.

Therefore, the degree of discharge by the discharge needle 4, that is, the amount of ions released from the discharge needle 4 can be detected by the potential difference V ₁ of the first resistor R ₁ , thereby reducing the performance or efficiency of the discharge needle 4. As well as the ion balance in the vicinity of the discharge needle 4. On the other hand, the ion balance in the vicinity of the workpiece W can be known from the potential difference V _{2 of} the second resistor R ₂ .

For example, the potential difference V ₁ of the first resistor R ₁ is detected by the ion current detection circuit 14, and this detection data is input to the CPU 15, and the potential difference V ₁ becomes extremely small or decreases with time. If it becomes smaller than this, it is sufficient to notify the operator by the alarm means or the display means 16 that the discharge is abnormal. Examples of this type of discharge abnormality include a case where dust is accumulated on the discharge needle 4.

Further, for example, the discharge needle is used so that the potential difference V ₂ of the second resistor R ₂ is detected by the ion current detection circuit 14 and this detection data is input to the CPU 15 to maintain the ion balance in the vicinity of the workpiece W. The feedback control for changing the pulse voltage for ion generation (typically pulse width) applied to 4 can be performed.

Further, the ion balance in the vicinity of the discharge needle 4 can be known by comparing the positive current value I ₁ or I ₂ with the negative current value I ₁ or I _2. Feedback control can be performed to change the pulse voltage (typically pulse width) for ion generation applied to the discharge needle 4 so as to keep it.

  The CPU 15 constitutes a static elimination control control means that operates in accordance with a static elimination control program for executing the static elimination control of the embodiment described below based on the drawings of FIG. 4 and subsequent drawings including the above-described ion balance feedback control. The time length of the interval period t included in this static elimination control, the number of pulses of the pulse voltage IP for ion generation in the ion emission cycle S, etc. may be set in advance, but various setting means are prepared for the static eliminator 1 Then, this setting means may allow the user to set the number of pulses of the ion generation pulse voltage in the ion emission cycle S, the time length of the interval period t, and the like.

  FIG. 4 is a diagram for explaining basic control related to static elimination of the static eliminator 1, in which the upper stage is a time chart for controlling the pulse voltage applied to the discharge needle 4, and the lower stage is the voltage at the tip of the discharge needle 4. Indicates. In the figure, reference symbol IP represents a pulse voltage for ion generation, and NP represents a pulse voltage for neutralizing a needle potential. In addition, (+) and (−) appended to the IP and NP indicate the polarity of each pulse voltage.

  In the basic control, the ion generation pulse voltages IP are all controlled to have the same pulse width and absolute voltage value. Several operation modes having different pulse widths and / or absolute voltage values of the ion generation pulse voltage used for the basic control may be prepared so that the user can select an appropriate operation mode.

  The needle potential neutralizing pulse voltage NP is fixed, and is controlled so that the pulse widths and absolute voltage values of all the needle potential neutralizing pulse voltages NP are constant. Also, for the interval period t, the time length of all the interval periods t is constant. As can be understood from FIG. 4, the ion emission cycle S in which the ion generation pulse voltages IP having different polarities are alternately applied to the discharge needle 4 is repeated with an interval period t, and the ion generation immediately before each interval period t is generated. The polarity of the pulse voltage IP for use and the polarity of the pulse voltage IP for ion generation immediately after are opposite in polarity. Further, at the beginning of the interval period t, immediately after the immediately preceding ion generating pulse voltage IP, the needle voltage neutralizing pulse voltage NP having a polarity opposite to the polarity of the ion generating pulse voltage IP is applied to the discharge needle 4. Applied.

  The needle voltage neutralizing pulse voltage NP is for neutralizing the potential remaining in the discharge needle 4 after entering the interval period t, and the optimum needle voltage neutralizing pulse voltage NP may be obtained by experiments. However, the discharge needle 4 has a pulse voltage that does not cause corona discharge even when the needle voltage neutralization pulse voltage NP is applied thereto. Therefore, the needle voltage neutralization pulse voltage NP is applied to the discharge needle 4. Even when applied, no ions are generated.

  In the basic control illustrated in FIG. 4, the number of pulses of the ion generation pulse voltage IP included in each ion emission cycle is “3”, but the number is not particularly limited as long as it is an odd number other than 1. For example, the number of pulses of the ion generation pulse voltage IP may be “5”, “7”, or an odd number greater than that.

  In addition, the polarity of the pulse voltage IP for ion generation immediately before each interval period t and the pulse voltage IP for ion generation immediately after that are opposite in polarity. That is, the last ion generation pulse voltage IP of the ion release cycle S (1) shown on the left side of FIG. 4 is positive, and the first ion generation pulse voltage IP of the next ion release cycle S (2) is negative. It is. In other words, the ion generation pulse voltage IP immediately before the interval period t (1) on the left side of FIG. 4 is positive, and the ion generation pulse voltage IP immediately before the next interval period t (2) is negative. .

  In the interval period t included in the basic control of FIG. 4, the discharge needle 4 does not substantially work. Therefore, by providing this interval period t, it is possible to prevent the discharge needle 4 from being contaminated as in the conventional case. In addition, since the polarity of the pulse voltage IP for ion generation immediately before each interval period t that influences the ion balance in the interval period t alternates, a good ion balance can be maintained over a long period of time. Further, in each ion release cycle S, both positive and negative ions are released, so that the static elimination speed of the workpiece W can be improved as compared with the conventional case.

  In order to maintain a good ion balance, it is preferable to reduce the bias of the ion balance in the interval period t. A modification of the basic control taking this into consideration is shown in FIG. In the control of FIG. 5, the pulse width and / or absolute voltage value of the ion generation pulse voltage IP at the end of each ion emission cycle S is decreased to reduce the ion generation amount in the latter half of each ion emission cycle S. is there. As described above, since the ion balance in the interval period t depends on the polarity of the immediately preceding ion generation pulse voltage IP, the ion generation pulse voltage IP (at least the last ion) in the second half of each ion emission cycle S. The pulse voltage for generation) is made smaller than the pulse voltage IP for other ions in each ion emission cycle S to reduce the amount of ion emission immediately before each interval period t, thereby reducing the ion balance in the interval period. Can be reduced. In the example of FIG. 5, the pulse widths of the two ion generation pulse voltages IP at the end of each ion emission cycle S are reduced as indicated by an arrow A.

  FIG. 6 shows an example in which the number of pulses of the ion generation pulse voltage IP in each ion emission cycle S is set to 7 times. Even when the basic control for applying the pulse voltage IP is adopted, in order to maintain a good ion balance, as in the above explanation with reference to FIG. It is preferable that the pulse width of the pulse voltage IP is reduced to reduce the bias of ion balance in the interval period t. Incidentally, in the example of FIG. 6, the pulse widths of the two ion generation pulse voltages IP at the end of each ion emission cycle S are reduced, but the last ion generation pulse of each ion emission cycle S is used. Only the pulse width of the voltage IP may be set to be small.

  The static eliminator manufacturer ships the static eliminator 1 for the pulse width and absolute voltage value of the ion generation pulse voltage IP at the end of each ion release cycle S, which is performed in order to reduce the bias of the ion balance in the interval period t. At this stage, it may be set in advance or may be arbitrarily set by the user.

  The static eliminator 1 may include various operation modes. For example, the first operation mode in accordance with the time chart shown in FIG. 4 and the second operation mode in accordance with the time chart shown in FIG. 5 or 6 are prepared, and the user manually operates such as a mode switching button. The first operation mode and the second operation mode may be selectively set by the mode switching means.

  As another example relating to the switching of the operation mode, the conventional typical AC pulse type neutralization control, that is, the neutralization of the pulse voltage for generating ions with different polarities is alternately applied to the discharge needle 4 alternately without an interval. You may prepare the operation mode without an interval which performs control, and the interval operation mode demonstrated with reference to FIG.

  The static eliminator 1 includes the feedback control of the ion balance as described with reference to FIG. 3. With regard to the feedback control of the ion balance, the static eliminator 1 is suitable when the above-described intervalless operation mode and interval operation mode are prepared. Such a method will be described below with reference to FIGS.

  As described above, in the no-interval operation mode, ion generation pulse voltages having different polarities are applied to the discharge needle 4 alternately and continuously. On the other hand, in the interval operation mode, in each ion emission cycle S, ion generation pulse voltages having different polarities are continuously and alternately applied to the discharge needle 4, but basically a high voltage is applied to the discharge needle 4. There is a pause period (interval period t) that is not performed. Therefore, when the ion generation pulse voltage immediately after the interval period t has passed is applied to the discharge needle 4, the needle tip voltage of the discharge needle 4 tends to rise sharply as shown by the arrow B in FIG. The rise of the needle tip voltage of the discharge needle 4 when the subsequent ion generation pulse voltage is applied to the discharge needle 4 tends to rise relatively slowly as indicated by an arrow C. Thus, in the interval operation mode, there are two types of transient response characteristics of the needle tip voltage of the discharge needle 4. On the other hand, in the continuous operation mode, pulse voltages for ion generation with different polarities are continuously and alternately applied to the discharge needle 4, so that the transient response characteristic of the needle tip voltage of the discharge needle 4 is one type. The transient response characteristic is common to the transient response characteristic C in the interval operation mode.

Therefore, the timing for measuring the current values I ₁ and / or I ₂ (or voltage values V ₁ and / or V ₂ ) (see FIG. 3) used for feedback control of ion balance is set to the second and subsequent times of each ion emission cycle S. By setting so as to synchronize with the ion emission timing, ion balance feedback control can be executed based on a common control expression applicable to both the interval operation mode and the intervalless operation mode.

In the interval operation mode shown in FIGS. 7 and 8, five ion generation pulse voltages IP are applied to the discharge needle 4 in each ion emission cycle S. Among them, the third ion generation pulse voltage IP indicated by hatching, that is, the ion generation pulse voltage that can discharge ions most stably immediately before the pulse width is reduced in order to maintain the ion balance in the interval period t. An example of measuring current values I ₁ and / or I ₂ (or voltage values V ₁ and / or V ₂ ) when applying IP to the discharge needle 4 is shown.

  Regarding the ion balance control, when the detected ion balance is biased to the plus side or the minus side, the ion generation pulse voltage IP applied to the discharge needle 4 is set so that the number of emitted ions having the opposite polarity can be relatively increased. Control is sufficient. As a typical method for this, for example, when the ion balance is biased to the minus side, the pulse width of the plus-side ion generation pulse voltage IP (+) is expanded, and the minus-side ion generation pulse voltage IP (− ), The ion balance can be corrected by increasing the amount of positively emitted ions and decreasing the amount of negatively emitted ions.

  With respect to the ion balance control, the positive or negative ion generation pulse voltage IP may be changed, and the ion generation pulse voltage IP having the opposite polarity may be controlled without changing the basic control. Specific examples of this control are shown in FIGS. FIG. 7 shows a control example when the ion balance is biased toward the minus side, and FIG. 8 shows a control example when the ion balance is biased toward the plus side.

  That is, when the ion balance is biased to the minus side, as shown in FIG. 7, the pulse width of the positive ion generation pulse voltage IP (+) is increased, while the negative side ion generation pulse voltage IP ( With regard to-), the basic pulse width remains unchanged, and the amount of positive emitted ions is relatively increased, thereby correcting the ion balance bias. Conversely, when the ion balance is biased to the plus side, as shown in FIG. 8, the pulse width of the plus ion generation pulse voltage IP (+) is reduced, while the minus side ion generation pulse voltage IP. By not changing the basic pulse width with respect to (−), it is possible to relatively reduce the amount of positive emitted ions and correct the ion balance bias. 7 and 8 show examples in which ion balance feedback control is added to the modified basic control example (FIG. 5), it goes without saying that the basic control in FIG. 4 can be similarly applied.

  As described above, as a specific method for changing the pulse width of the ion generation pulse voltage by feedback control of the ion balance, the predetermined pulse width is uniformly increased or decreased with respect to the pulse width of the basic ion generation pulse voltage. Alternatively, the pulse width of the basic ion generation pulse voltage may be increased or decreased by a ratio corresponding to the amount of deviation of the ion balance.

  As described above, when the control is performed to change the pulse voltage IP for generating ions, the residual voltage of the discharge needle 4 cannot be neutralized suitably with the fixed pulse voltage NP for neutralizing the needle voltage. Including sex. With respect to this problem, the neutralization of the residual voltage of the discharge needle 4 is optimized by adding control for changing the needle voltage neutralization pulse voltage NP according to the ion generation pulse voltage IP immediately before the interval period t is entered. be able to.

  FIG. 9 shows a change in the pulse width of the pulse voltage NP for neutralizing the needle voltage immediately after that in accordance with the pulse width of the pulse voltage IP for the last ion generation in each ion emission cycle S that affects the residual voltage of the discharge needle 4. An example of control is shown. As a specific control example, for example, when the pulse width of the last ion generation pulse voltage IP of each ion emission cycle S is increased by 10% with respect to the pulse width of the basic ion generation pulse voltage, the needle The residual voltage of the discharge needle 4 may be neutralized at an early stage by expanding the pulse width of the voltage neutralizing pulse voltage NP by 10% or by multiplying the pulse width by a predetermined coefficient.

  FIG. 9 shows the variation of the basic control for reducing the bias of the ion balance in the interval period t (FIG. 5) according to the pulse width of the last ion generation pulse voltage IP in each ion emission cycle S. The example in which the pulse width of the needle voltage neutralizing pulse voltage NP is changed has been shown, but it goes without saying that the basic control of FIG. 4 can be similarly applied.

  Next, a modification regarding variable control of the needle voltage neutralizing pulse voltage NP will be described. For example, in the ion balance feedback control described with reference to FIGS. 7 and 8, only the positive-side ion generation pulse voltage IP (+) is changed, but this positive ion-generation pulse voltage IP (+ ), The frequency of ion emission changes. Therefore, the control for optimizing the pulse voltage NP for needle voltage neutralization is performed by measuring this frequency and adding control for changing the pulse width of the pulse voltage NP for needle voltage neutralization corresponding to the frequency. It may be.

  In the feedback control examples of FIGS. 7 and 8, the pulse width of the negative ion generation pulse voltage IP (−) is fixed. Therefore, when the last ion generation pulse voltage IP of each ion emission cycle S is negative, the pulse width of the positive needle voltage neutralization pulse voltage NP (+) immediately after that is not changed, and each ion emission cycle is not changed. Only when the pulse voltage IP for the last ion generation of S is positive, the pulse width of the pulse voltage NP (-) for neutralizing the needle voltage immediately after S is in accordance with the ion emission frequency. Control is performed such that the pulse width of the sum pulse voltage NP (-) is relatively small, and the pulse width of the needle voltage neutralization pulse voltage NP (-) is relatively large when the frequency is relatively small.

  As another method, when the last ion generation pulse voltage IP of each ion release cycle S has a variable polarity, as in the feedback control of FIGS. 7 and 8, the last ion generation is performed. Based on the pulse width of the pulse voltage IP, the pulse width of the pulse voltage NP for neutralization of the reverse polarity immediately after that is changed, and the pulse voltage IP for ion generation at the end of each ion emission cycle S is fixed. In the case of polarity, the needle immediately after the ion release cycle S is based on the pulse width of the ion generation pulse voltage IP of the reverse polarity that is variably controlled immediately before the last ion generation pulse voltage IP. The pulse width of the voltage neutralizing pulse voltage NP may be changed. That is, in each ion emission cycle S, the pulse width of the needle voltage neutralization pulse voltage NP immediately after the ion emission cycle S is changed based on at least the pulse width of the last variable-side ion generation pulse voltage IP. By performing the control, the residual voltage of the discharge needle 4 can be neutralized early.

  The above concept is not limited to the case where the positive or negative ion generation pulse IP of each ion emission cycle S is variably controlled. Both positive and negative ion generation pulse voltages IP are used. This can also be applied to the case where the control is variably controlled. That is, when both the positive and negative ion generation pulse voltages IP are variably controlled, the positive and negative ion generation pulse voltages IP are variable, but the variable ion generation for each ion release cycle S is possible. Based on the pulse width of the pulse voltage IP, the pulse voltage IP for generating ions of one polarity described above is fixed in that the pulse width of the pulse voltage NP for neutralizing the needle voltage immediately after the ion emission cycle S is changed. This is common with the case of changing the ion generating pulse voltage IP of the other polarity. Needless to say, in each ion emission cycle S, not only the variable width of the final variable ion generation pulse voltage IP but also all other variable ion generation pulses of the ion emission cycle S are concerned. In consideration of the width condition, it is also possible to set the change amount of the pulse width of the pulse voltage NP for neutralizing the needle voltage immediately after the ion emission cycle S.

It is a figure for demonstrating the outline | summary of the static elimination control method of patent document 1 of a prior art example. It is a figure for demonstrating the outline | summary of the static elimination control method of this invention. It is a circuit diagram of the static eliminator of an Example. It is a time chart for demonstrating the basic control of the static elimination control method of an Example. It is a time chart for demonstrating the modification of the basic control of the static elimination control method of an Example. It is a time chart for demonstrating an example of the control for maintaining the ion balance of an interval period favorable. Example of performing ion balance feedback control by changing the pulse width of the positive ion generation pulse voltage while fixing the pulse width of the negative ion generation pulse voltage when performing feedback control of ion balance Is a time chart showing a control example when the ion balance is biased to the minus side. FIG. 8 is a time chart showing a control example when the ion balance is biased toward the plus side in relation to FIG. 7. It is a figure for demonstrating the method to variably control the pulse voltage for needle voltage neutralization applied to a discharge needle at the beginning of an interval period.

Explanation of symbols

4, 100 Discharge needle S Ion release cycle IP Ion generation pulse voltage NP Needle voltage neutralization pulse voltage t interval period G Release ion group corresponding to ion release cycle

Claims (7)

A static elimination control method for a static eliminator that alternately discharges positive ions and negative ions by alternately applying pulse voltages for ion generation with different polarities to the same discharge needle,
An ion emission process in which an ion emission cycle in which a plurality of pulse voltages for generating ions having different polarities are alternately applied to the discharge needle is repeated at intervals, and
At the beginning of the interval period, a needle voltage neutralizing pulse voltage for neutralizing the residual potential of the discharge needle having a polarity opposite to that of the ion generating pulse voltage immediately before the interval period is applied to the discharge needle. A needle voltage neutralization step,
In each ion emission cycle, the ion generation pulse voltage is applied to the discharge needle an odd number of times, and the ion generation pulse voltage immediately before the interval period and the ion generation pulse voltage immediately before the next interval period And a neutralization control method for the static eliminator, characterized in that and are opposite in polarity. The pulse width and / or absolute voltage value of at least the last ion generation pulse voltage of each ion emission cycle is set to be smaller than the other ion generation pulse voltages. The static elimination control method of the static eliminator according to claim 1, wherein the bias of ion balance in the interval period is reduced by decreasing the amount. The static elimination control method of the static eliminator according to claim 1 or 2, wherein the static eliminator has a plurality of operation modes having different time lengths of the interval period. A feedback step for controlling the ion generation pulse voltage to correct the deviation of the ion balance when the detected ion balance is deviated to the plus or minus side;
The static elimination control method for a static eliminator according to any one of claims 1 to 3, wherein, in the feedback step, a reverse ion generation pulse voltage is variably controlled while a positive or negative ion generation voltage is fixed. . An interval operation mode in which the static eliminator repeatedly performs the ion emission cycle after the interval period, and an interval in which pulse voltages for generating ions having different polarities are applied alternately to the discharge needle without the interval. No operation mode, and
When the ionization control method detects the ion balance and the detected ion balance is biased to the plus or minus side, a feedback step of controlling the ion generation pulse voltage to correct the ion balance bias. In addition,
5. In the interval operation mode, the ion balance is detected in synchronization with a timing of applying ions to the discharge needle at the second and subsequent ion generation pulse voltages in the ion emission cycle. The static elimination control method of the static eliminator as described in any one of these. The neutralization of the residual potential of the discharge needle is optimized by controlling the pulse voltage for neutralizing the needle voltage according to at least the last pulse voltage for generating ions in the ion emission cycle. The static elimination control method of the static eliminator as described in any one. Measuring the frequency of the emitted ions of the ion emission cycle;
The neutralization of the residual potential of the discharge needle is optimized by controlling the pulse voltage for neutralizing the needle voltage according to the frequency of the emitted ions. Static elimination control method for electrical appliances.

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